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   2897篇
  免费   211篇
  国内免费   76篇
耳鼻咽喉   17篇
儿科学   240篇
妇产科学   36篇
基础医学   443篇
口腔科学   63篇
临床医学   338篇
内科学   614篇
皮肤病学   79篇
神经病学   106篇
特种医学   437篇
外科学   168篇
综合类   61篇
预防医学   197篇
眼科学   24篇
药学   161篇
  2篇
肿瘤学   198篇
  2022年   20篇
  2021年   23篇
  2020年   19篇
  2019年   28篇
  2018年   40篇
  2017年   28篇
  2016年   30篇
  2015年   48篇
  2014年   65篇
  2013年   83篇
  2012年   69篇
  2011年   70篇
  2010年   103篇
  2009年   99篇
  2008年   65篇
  2007年   118篇
  2006年   78篇
  2005年   90篇
  2004年   48篇
  2003年   49篇
  2002年   58篇
  2001年   68篇
  2000年   53篇
  1999年   60篇
  1998年   146篇
  1997年   166篇
  1996年   147篇
  1995年   116篇
  1994年   122篇
  1993年   109篇
  1992年   47篇
  1991年   48篇
  1990年   63篇
  1989年   69篇
  1988年   65篇
  1987年   62篇
  1986年   72篇
  1985年   71篇
  1984年   47篇
  1983年   35篇
  1982年   40篇
  1981年   45篇
  1980年   37篇
  1979年   30篇
  1978年   24篇
  1977年   39篇
  1976年   38篇
  1975年   29篇
  1974年   12篇
  1973年   12篇
排序方式: 共有3184条查询结果,搜索用时 15 毫秒
41.
42.
High-dose (HD) cytosine arabinoside (ARA-C) is more effective treatment than conventional-dose ARA-C regimens for patients with relapsed acute nonlymphocytic leukemia (ANLL). We report here that HD ARA-C given during the first remission of ANLL has resulted in long remission durations and a high proportion of patients who survive more than three years free of disease. From August 1979 to September 1983, 36 adult patients with ANLL in first remission received one to three courses of HD ARA-C (3 g/m2 by one-hour infusion every 12 hours for 12 doses on days 1 through 6) alone or with daunorubicin (30 mg/m2 for two or three doses on days 7 through 9). Three patients died of sepsis or hemorrhage during consolidation, and 14 patients have relapsed from five to 48 months after diagnosis. The remaining 19 patients are in continued complete remission (CCR) from 11 to 62 months. Denoting all deaths in remission as relapse, the actuarial probability of CCR is 42% at 62 months, with an apparent plateau in the survival curve. Of the first 22 patients treated, ten remain in CCR from 37 to 62 months with no therapy for at least three years. Due to its heightened anti-leukemic activity, HD ARA-C allows brief but effective consolidation of ANLL in first remission, with long-term disease-free survival comparable to other approaches.  相似文献   
43.
In 22 patients with malignancies, treated with high-dose chemoradiotherapy and autologous bone marrow transplantation (BMT), peripheral blood T cell subsets and functions were studied. In ten cytomegalovirus (CMV)-negative patients, CD4+ and CD8+ T cells (representing T cells of the helper/inducer phenotype and T cells of the suppressor/cytotoxic phenotype, respectively), recovered slowly and simultaneously. In 12 CMV-positive patients, however, CD8+ T cells recovered more rapidly than CD4+ T cells and rose to increased counts. No T cells with an immature phenotype (CD1+, OKT6+) were observed. Lymphocyte stimulation by herpes simplex virus infected fibroblasts (and by CMV-infected fibroblasts in CMV-positive patients) in contrast remained high and even increased after BMT in both groups. These data indicate that T cell recovery after autologous BMT is mainly due to proliferation of mature T cells present in the BM graft and not to generation of new T cells from T cell precursors.  相似文献   
44.
Although estradiol (E2) alone does not increase receptors for FSH in granulosa cells, E2 priming before administration of FSH increases numbers of FSH receptors significantly compared with FSH alone. We hypothesized that if E2 is required for FSH to increase its own receptor, blocking estrogen action should prevent FSH-induced increases in FSH receptors. Five groups of hypophysectomized rats were injected sc with: saline at 0 h; the antiestrogen CI628 (1 mg) at -6 h; human FSH (hFSH, 2 micrograms) at 0 h; CI628 at -6 h, then hFSH at 0 h; and CI628 plus E2 (2 mg) at -6 h, then FSH at 0 h. Animals were decapitated at 0, 6, 12, or 24 h, and granulosa membrane receptors for FSH, LH, and nuclear receptors for E2 were measured. LH receptor levels increased only after administration of E2 before hFSH. Treatment with hFSH for 6 h increased numbers of FSH receptors 3-fold (P less than 0.01) without any increase in numbers of E2 receptors. At 12 and 24 h, hFSH increased numbers of FSH and E2 receptors 6- and 7-fold (P less than 0.01) over controls. CI628 prevented the hFSH-induced increases in FSH receptors at 6, 12, and 24 h. Administration of E2 concomitant with CI628 before hFSH significantly reversed the inhibitory effects of CI628 on hFSH-induced increases in FSH receptors. There were no changes in affinity of FSH or E2 receptors from 0 to 24 h. To determine whether E2 was acting on the adenylate cyclase system, the ability of hFSH to increase the content of cAMP in granulosa cells in each treatment group was determined. After an iv injection of hFSH, cAMP levels were similar in CI628- and saline-treated rats but had increased 6-fold (P less than 0.01) in hFSH or CI628 plus hFSH-treated animals. Thus, blocking hFSH-induced increases in FSH and E2 receptor appeared to have no effect on FSH stimulation of cAMP. In conclusion E2 appears to be required for FSH action, perhaps by acting within granulosa cells distal to the cAMP-adenylate cyclase system.  相似文献   
45.
In 28 of 1656 total knee arthroplasties (TKAs) (1.7%) performed for osteoarthritis at this institution, the preoperative arc of motion was 60 degrees or less (average 47.5 degrees; range, 20-60 degrees). The outcome of 22 of the 28 TKAs (21 patients) is reported at a mean follow-up of 52.9 months (range, 24-144 months). Eighty-two percent of the cases were managed with standard soft-tissue releases and posterior cruciate-retaining implants and 18% with a cruciate-substituting design. The joint score rose from 28.8 to 82.2 and the Knee Society Score from 24.6 to 77 points. The mean postoperative arc of motion improved by 46 degrees-93.5 degrees. At latest follow-up, 68.2% of knees achieved maximal flexion of 90 degrees or more. Manipulation was performed in 22.7%. Complications were minimal. A functionally useful range of motion is possible after total knee arthroplasty in the majority of stiff osteoarthritic knees, often without the need for posterior cruciate substitution.  相似文献   
46.

Purpose

We compared renal function outcomes among patients in the surveillance and intervention arms of the DISSRM registry.

Materials and methods

Patients were grouped into chronic kidney disease stages by estimated glomerular filtration rate range. Cases were considered up staged if a more advanced chronic kidney disease stage was entered during followup. Chronic kidney disease up staging-free survival was compared among groups using Kaplan-Meier analysis and paired comparisons log rank tests. Multivariate Cox regression identified independent predictors of chronic kidney disease up staging-free survival.

Results

A total of 162 patients met the study inclusion criteria, with 68 in the surveillance arm, 65 undergoing partial nephrectomy, 15 undergoing radical nephrectomy, and 14 undergoing cryoablation. Median tumor size was 2.2 cm. Mean estimated glomerular filtration rate change was significantly larger for radical nephrectomy vs. surveillance (?9.2 vs. ?0.5 ml/min/1.73 m2) and for radical vs. partial nephrectomy (?9.2 vs. ?1.9 ml/min/1.73 m2) (P = 0.001). No other groups differed significantly. On Kaplan-Meier analysis, patients undergoing radical nephrectomy had significantly worse chronic kidney disease up staging-free survival vs. those treated with partial nephrectomy (P = 0.029), surveillance (P = 0.007), and cryoablation (P = 0.019). No other groups differed significantly. On multivariate analysis, radical nephrectomy independently predicted poor chronic kidney disease up staging-free survival (odds ratio vs. surveillance 30.6, P = 0.001). Neither partial nephrectomy (P = 0.985) nor cryoablation (P = 0.976) predicted poor chronic kidney disease up staging-free survival relative to surveillance.

Conclusions

Patients in the surveillance arm had superior estimated glomerular filtration rate preservation compared to those in the radical nephrectomy but not the partial nephrectomy arm. In certain patients with small renal masses, surveillance and partial nephrectomy may offer comparable renal functional outcomes. This could be partly attributable to a modest estimated glomerular filtration rate decrease associated with surveillance itself. A thorough understanding of the renal functional impacts of treatment modalities is critical in the management of small renal masses.  相似文献   
47.
48.
In clonogenic assays of hematopoietic progenitors, high concentrations (4 U/mL) of erythropoietin (epo) reduced the formation of granulocyte- macrophage (GM) colonies and diminished the number of granulocytes formed per culture plate. Fetal progenitors were more sensitive to these effects of epo than were progenitors from adults, displaying these reductions at greater than or equal to 1 U epo/mL. The mechanism was investigated by growing fetal progenitors stimulated by recombinant GM-CSF, in the absence of epo, and when eight-cell clones first appeared, mapping their location, then adding epo, and assessing its effect on the subsequent differentiation of the clones. In the absence of epo, the clones developed exclusively into GM colonies. However, if developing clones were presented with epo, 85% matured into GM colonies, but 15% became multilineage or normoblast colonies. In addition, developing clones that were presented with epo produced colonies that contained fewer neutrophils. These effects of epo on neutrophil generation were observed with each of three varieties of recombinant epo, and also with purified human epo, but were not observed using epo that had been neutralized with rabbit anti-epo antiserum.  相似文献   
49.
The ileoanal J pouch: radiographic evaluation   总被引:1,自引:0,他引:1  
Hillard  AE; Mann  FA; Becker  JM; Nelson  JA 《Radiology》1985,155(3):591-594
Endorectal ileoanal pull-through offers an attractive alternative to proctocolectomy and ileostomy for patients with ulcerative colitis, Gardner syndrome, and familial polyposis. To our knowledge, a careful radiographic analysis of the ileum, ileal pouch, and ileoanal anastomosis after ileoanal pull-through has not been reported. Thirty-two patients with ulcerative colitis, Gardner syndrome, and familial polyposis underwent colectomy, mucosal proctectomy, and endorectal ileoanal pull-through of a 15-cm ileal "J" pouch and loop ileostomy. Twenty-five (78%) of 32 of all the pouches radiographically demonstrated spiral folds extending from the middle of the pouch to the pectinate line. Other radiographic features included a mesenteric mass effect, pseudopolyps, and a central lucency that indicated intrapouch sutures. Radiographs provide useful information in the postoperative management of the ileal pull-through.  相似文献   
50.
We have used the long-term bone marrow culture (LTBMC) system to analyze hematopoiesis in three patients with dyskeratosis congenita (DC), two of whom had aplastic anemia, and the third had a normal blood count (apart from mild macrocytosis) and normal BM cellularity. Hematopoiesis was severely defective in all three patients, as measured by a low incidence of colony-forming cells and a low level of hematopoiesis in LTBMC. The function of the marrow stroma was normal in its ability to support the growth of hematopoietic progenitors from normal marrows seeded onto them in all three cases, but the generation of hematopoietic progenitors from patients marrow cells inoculated onto normal stromas was reduced, thus suggesting the defect to be of stem cell origin. The parents and unaffected brother of one of the families have also been studied in LTBMC and all showed normal hematopoietic and stromal cell function. From this study we speculate that there are some similarities between DC and the defect in the W/Wv mouse.  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