首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   8394篇
  免费   995篇
  国内免费   22篇
耳鼻咽喉   91篇
儿科学   269篇
妇产科学   261篇
基础医学   931篇
口腔科学   132篇
临床医学   1977篇
内科学   1302篇
皮肤病学   96篇
神经病学   929篇
特种医学   333篇
外国民族医学   1篇
外科学   966篇
综合类   186篇
一般理论   7篇
预防医学   1036篇
眼科学   157篇
药学   370篇
中国医学   7篇
肿瘤学   360篇
  2023年   83篇
  2022年   49篇
  2021年   132篇
  2020年   110篇
  2019年   118篇
  2018年   229篇
  2017年   209篇
  2016年   190篇
  2015年   175篇
  2014年   245篇
  2013年   304篇
  2012年   411篇
  2011年   375篇
  2010年   232篇
  2009年   245篇
  2008年   331篇
  2007年   364篇
  2006年   308篇
  2005年   335篇
  2004年   346篇
  2003年   326篇
  2002年   249篇
  2001年   253篇
  2000年   249篇
  1999年   228篇
  1998年   136篇
  1997年   134篇
  1996年   117篇
  1995年   167篇
  1994年   187篇
  1993年   154篇
  1992年   228篇
  1991年   189篇
  1990年   165篇
  1989年   181篇
  1988年   167篇
  1987年   127篇
  1986年   127篇
  1985年   127篇
  1984年   102篇
  1983年   89篇
  1982年   62篇
  1979年   83篇
  1978年   47篇
  1977年   55篇
  1976年   50篇
  1974年   57篇
  1973年   62篇
  1972年   56篇
  1969年   48篇
排序方式: 共有9411条查询结果,搜索用时 15 毫秒
991.
Lee K  Solts B  Burns J 《AIDS care》2002,14(6):851-857
Developments in anti-HIV medication have meant that people with HIV/AIDS are now living longer, with some authors arguing that HIV should now be defined as a manageable rather than terminal illness. However uncertainty about the long-term efficacy of such treatments remains. This research aimed to examine the psychosocial impact of the new treatments and to explore whether, and in what ways, they affect psychological wellbeing. Clients were also asked about their use of services and whether they thought services should be changing in response to new pharmacological treatments. A semi-structured interview schedule was developed to elicit the views of six service users. From multiple readings of the qualitative data generated, prominent themes were identified suggesting that participants had ambivalent feelings about taking antiretroviral combination therapy and that being well with HIV raised a number of difficult issues. Four main themes were revealed: (1) disruptions in daily living: antiretrovirals as intrusions to life, (2) the tablets as a visible marker for HIV infection, (3) tempered optimism and increasing horizons, (4) an uncertain and fragile future: life without benefits and services. The results were discussed in terms of limitations of the current study and suggestions for further research.  相似文献   
992.
Lymphoblastic lymphoma (LBL) is a rare, clinically aggressive neoplasm of the young that frequently involves the bone marrow (BM) and/or central nervous system. Because LBL is similar to acute lymphoblastic leukemia, some centers prefer allogeneic hematopoietic stem cell (SC) transplantation to autologous SC transplantation. We retrospectively analyzed outcomes for patients who underwent autologous (auto, n = 128) or HLA-identical sibling (allo, n = 76) SC transplantations from 1989 to 1998 and were reported to International Bone Marrow Transplant Registry (IBMTR) or Autologous Blood and Marrow Transplant Registry (ABMTR). Allo stem cell transplant (SCT) recipients had higher treatment-related mortality (TRM) at 6 months (18% versus 3%, P =.002), and this disadvantage persisted at 1 and 5 years. Early relapse rates after alloSC transplantation and autoSC transplantation were similar, but significantly lower relapse rates were observed in alloSCT recipients at 1 and 5 years (32% versus 46%, P =.05; and 34% versus 56%, P =.004, respectively). No differences were noted in lymphoma-free survival rates between alloSC transplantations and autoSC transplantations (5-year rates 36% versus 39%, P =.82). AutoSCT recipients had higher overall survival at 6 months (75% versus 59%, P =.01), but survival did not significantly differ between the 2 groups at 1 and 5 years (60% versus 49%, P =.09; 44% versus 39%, P =.47, respectively). Multivariate analyses to account for confounding factors confirmed these results. Independent of SCT type, BM involvement at the time of transplantation and disease status more advanced than first complete remission were associated with inferior outcomes. In summary, alloSC transplantation for LBL is associated with fewer relapses than with autoSC transplantation, but higher TRM offsets any potential survival benefit.  相似文献   
993.
Nutrition knowledge in the obese and overweight   总被引:3,自引:0,他引:3  
A 20-question multiple choice questionnaire on nutrition knowledge, health care and exercise was developed and validated (Cronbach alpha 0.83). When applied to a population of the obese and overweight, these individuals scored well (63.5 +/- 1.4 per cent) compared to other hospital patients (50.2 +/- 1.7 per cent), and out-patients (47.7 +/- 2.3 per cent). There was no difference between scores in patients presenting to a hospital clinic (who were heavier) and those presenting in the community. Even allowing for age and sex, the obese and overweight scored better than other groups (P less than 0.005). There was no relationship between knowledge score and weight. A group of overweight patients with non-insulin-dependent diabetes mellitus scored poorly (42.3 +/- 2.3 per cent). From this study it was apparent that good nutrition and health care knowledge is not necessarily related to good weight control, other factors seem limiting in this sample. The questionnaire itself may be used to assess whether change in knowledge following nutrition education is related to weight loss.  相似文献   
994.
OBJECTIVES: To evaluate the effect of an exercise‐based model of hospital and in‐home follow‐up care for older people at risk of hospital readmission on emergency health service utilization and quality of life. DESIGN: Randomized controlled trial. SETTING: Tertiary metropolitan hospital in Australia. PARTICIPANTS: One hundred twenty‐eight patients (64 intervention, 64 control) with an acute medical admission, aged 65 and older and with at least one risk factor for readmission (multiple comorbidities, impaired functionality, aged ≥75, recent multiple admissions, poor social support, history of depression). INTERVENTION: Comprehensive nursing and physiotherapy assessment and individualized program of exercise strategies and nurse‐conducted home visit and telephone follow‐up commencing in the hospital and continuing for 24 weeks after discharge. MEASUREMENTS: Emergency health service utilization (emergency hospital readmissions and visits to emergency department, general practitioner (GP), or allied health professional) and health‐related quality of life (Medical Outcomes Study 12‐item Short Form Survey (SF‐12v2?) collected at baseline and 4, 12, and 24 weeks after discharge. RESULTS: The intervention group required significantly fewer emergency hospital readmissions (22% of intervention group, 47% of control group, P=.007) and emergency GP visits (25% of intervention group, 67% of control group, P<.001). The intervention group also reported significantly greater improvements in quality of life than the control group as measured using SF‐12v2? Physical Component Summary scores (F (3, 279)=30.43, P<.001) and Mental Component Summary scores (F (3, 279)=7.20, P<.001). CONCLUSION: Early introduction of an individualized exercise program and long‐term telephone follow‐up may reduce emergency health service utilization and improve quality of life of older adults at risk of hospital readmission.  相似文献   
995.
The Diagnosis and Staging Working Group of the NIH Consensus Development Project on Criteria for Clinical Trials in chronic GVHD (CGVHD) recently proposed criteria for diagnosis and assessment of overall CGVHD severity. We retrospectively reviewed 54 consecutive patients diagnosed with CGVHD between January 2002 and December 2005 after sibling donor transplant to assess the applicability of the new criteria in prognosticating survival and transplant-related mortality (TRM). A total of 8 patients (15%) were reclassified as late onset/persistent or recurrent acute GVHD (late aGVHD), 15 (28%) had overlap syndrome and 31 (57%) had classic CGVHD. Three-year overall survival was worse in patients with late aGVHD (3-year probability 25% (95% CI 4-56%)) followed by overlap syndrome (3-year probability 87% (95% CI 56-96%)) and CGVHD (3-year probability 75% (95% CI 54-87%)); P=0.001. Among patients with overlap syndrome and CGVHD, a trend towards worse survival was seen in patients with severe disease (3-year probability 57.3% (95% CI 21-82%)) as compared to mild+moderate disease (3-year probability 85.1% (95% CI 68-94)); P=0.1. This analysis, undertaken in a contemporary cohort of related donor recipients, indicates that the consensus guidelines are applicable to this population of CGVHD patients.  相似文献   
996.
The retina's photoreceptor cells adjust their sensitivity to allow photons to be transduced over a wide range of light intensities. One mechanism thought to participate in sensitivity adjustments is Ca(2+) regulation of guanylate cyclase (GC) by guanylate cyclase-activating proteins (GCAPs). We evaluated the contribution of GCAPs to sensitivity regulation in rods by disrupting their expression in transgenic mice. The GC activity from GCAPs-/- retinas showed no Ca(2+) dependence, indicating that Ca(2+) regulation of GCs had indeed been abolished. Flash responses from dark-adapted GCAPs-/- rods were larger and slower than responses from wild-type rods. In addition, the incremental flash sensitivity of GCAPs-/- rods failed to be maintained at wild-type levels in bright steady light. GCAP2 expressed in GCAPs-/- rods restored maximal light-induced GC activity but did not restore normal flash response kinetics. We conclude that GCAPs strongly regulate GC activity in mouse rods, decreasing the flash sensitivity in darkness and increasing the incremental flash sensitivity in bright steady light, thereby extending the rod's operating range.  相似文献   
997.
The goal of this phase II multicenter clinical trial was to evaluate a new intensive chemotherapy program for adults with untreated acute lymphoblastic leukemia (ALL) and to examine prospectively the impact of clinical and biologic characteristics on the outcome. One hundred ninety-seven eligible and evaluable patients (16 to 80 years of age; median, 32 years of age) received cyclophosphamide, daunorubicin, vincristine, prednisone, and L-asparaginase; 167 patients (85%) achieved a complete remission (CR), 13 (7%) had refractory disease, and 17 (9%) died during induction. A higher CR rate was observed in younger patients (94% for those < 30 years old, 85% for those 30 to 59 years old, and 39% for those > or = 60 years old, P < .001) and in those who had a mediastinal mass (100%) or blasts with a T-cell immunophenotype. Eighty percent of B-lineage and 97% of T-cell ALL patients achieved a CR (P = .01). The coexpression of myeloid antigens did not affect the response rate or duration. Seventy percent of those with cytogenetic or molecular evidence of the Philadelphia (Ph) chromosome and 84% of those without such evidence achieved a CR (P = .11). Patients in remission received multiagent consolidation treatment, central nervous system prophylaxis, late intensification, and maintenance chemotherapy for a total of 24 months. After a median follow-up time of 43 months, the median survival for all 197 patients is 36 months; the median remission duration for the 167 CR patients is 29 months. Favorable pretreatment characteristics relative to remission duration or survival are younger age, the presence of a mediastinal mass or lymphadenopathy, a white blood cell count (WBC) less than 30,000/microL, L1 morphology, T or TMy immunophenotype, and the absence of the Ph chromosome. The estimates of the proportion surviving at 3 years are 69% for patients less than 30 years old, 39% for those 30 to 59 years old, 89% for those who had a mediastinal mass, 59% with WBC less than 30,000/microL, 63% with L1 morphology, 69% for T or TMy antigen expression, and 62% for those who lack the Ph chromosome. Fifteen patients (8%) had no unfavorable prognostic factors and have an estimated probability of survival at 5 years of 100% (95% confidence interval, 77% to 100%). This intensive chemotherapy regimen produces a high remission rate and a high proportion of durable remissions in adults with ALL.  相似文献   
998.
The rat cell line REF52 is not permissive for gene amplification. Simian virus 40 tumor (T) antigen converts these cells to a permissive state, as do dominant negative mutants of p53, suggesting that the effect of T antigen is due mainly to its ability to bind to p53. To manipulate permissivity, we introduced a temperature-sensitive mutant of T antigen (tsA58) into REF52 cells and selected for resistance to N-(phosphonacetyl)-L-aspartate (PALA). Most freshly isolated PALA-resistant colonies, each of approximately 200 cells, selected at a permissive temperature, arrested when shifted to a nonpermissive temperature. Growth arrest was stable, with no evidence of apoptosis, as long as T antigen was absent but was reversed when T antigen was restored. In contrast, PALA-resistant clones grown to approximately 10(7) cells at a permissive temperature did not arrest when shifted to a nonpermissive temperature. All PALA-resistant clones examined had amplified carbamoyl-phosphate synthetase-aspartate transcarbamoylase-dihydroorotase (CAD) genes, present in structures consistent with a mechanism involving bridge-breakage-fusion (BBF) cycles. We propose that p53-mediated growth arrest operates only early during the complex process of gene amplification, when newly formed PALA-resistant cells contain broken DNA, generated in BBF cycles. During propagation under permissive conditions, the broken DNA ends are healed, and, even though the p53-mediated pathway is still intact at a nonpermissive temperature and the cells contain amplified DNA, they are not arrested in the absence of broken DNA. The data support the hypothesis that BBF cycles are an important mechanism of amplification and that the broken DNA generated in each cycle is a key signal that regulates permissivity for gene amplification.  相似文献   
999.
Protein kinase C (PKC) is involved in the proliferation and differentiation of many cell types. In human erythroleukemia (K-562) cells, the PKC isoforms alpha and beta II play distinct functional roles. alpha PKC is involved in phorbol 12-myristate 13-acetate-induced cytostasis and megakaryocytic differentiation, whereas beta II PKC is required for proliferation. To identify regions within alpha and beta II PKC that allow participation in these divergent pathways, we constructed chimeras in which the regulatory and catalytic domains of alpha and beta II PKC were exchanged. These PKC chimeras can be stably expressed, exhibit enzymatic properties similar to native alpha and beta II PKC in vitro, and participate in alpha and beta II PKC isotype-specific pathways in K-562 cells. Expression of the beta/alpha PKC chimera induces cytostasis in the same manner as overexpression of wild-type alpha PKC. In contrast, the alpha/beta II PKC chimera, like wild-type beta II PKC, selectively translocates to the nucleus and leads to increased phosphorylation of the nuclear envelope polypeptide lamin B in response to bryostatin-1. Therefore, the catalytic domains of alpha and beta II PKC contain determinants important for alpha and beta II PKC isotype function. These results suggest that the catalytic domain represents a potential target for modulating PKC isotype activity in vivo.  相似文献   
1000.
Abstract Background: Many cases of small cell lung cancer will occur in the elderly population but optimal management of the disease in this age group remains uncertain.
Aims: To evaluate treatment of small cell lung cancer in the elderly in Australia and to compare treatment received and outcomes with those of younger patients. To draw insights from these observations into the optimal management of small cell lung cancer in the elderly.
Methods: A retrospective review of treatment charts and case notes for 51 elderly patients and 102 younger patients was undertaken.
Results: Elderly patients had similar baseline parameters with respect to disease stage and performance status. Elderly patients were mostly treated uniformly with combination chemotherapy, but suffered more dose reductions than younger patients. Benefits of chemotherapy were seen even in patients with poor performance status. Despite the dose reductions, response rates and survival times for elderly patients were usually similar to younger patients.
Conclusions: Combination chemotherapy is beneficial to elderly patients with small cell lung cancer. Optimal therapy for the elderly may be different from that for younger patients and should be defined through prospective randomised clinical trials.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号