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   2153篇
  免费   121篇
  国内免费   3篇
耳鼻咽喉   44篇
儿科学   89篇
妇产科学   48篇
基础医学   324篇
口腔科学   104篇
临床医学   204篇
内科学   387篇
皮肤病学   26篇
神经病学   201篇
特种医学   35篇
外科学   340篇
综合类   21篇
预防医学   166篇
眼科学   34篇
药学   116篇
中国医学   1篇
肿瘤学   137篇
  2023年   13篇
  2022年   46篇
  2021年   82篇
  2020年   47篇
  2019年   71篇
  2018年   86篇
  2017年   66篇
  2016年   46篇
  2015年   59篇
  2014年   88篇
  2013年   116篇
  2012年   165篇
  2011年   175篇
  2010年   92篇
  2009年   68篇
  2008年   130篇
  2007年   114篇
  2006年   102篇
  2005年   128篇
  2004年   93篇
  2003年   81篇
  2002年   68篇
  2001年   29篇
  2000年   35篇
  1999年   42篇
  1998年   13篇
  1997年   12篇
  1996年   10篇
  1995年   14篇
  1994年   14篇
  1993年   10篇
  1992年   17篇
  1991年   18篇
  1990年   16篇
  1989年   21篇
  1988年   14篇
  1987年   16篇
  1986年   9篇
  1985年   8篇
  1984年   7篇
  1983年   12篇
  1982年   5篇
  1981年   3篇
  1980年   1篇
  1979年   4篇
  1977年   1篇
  1974年   1篇
  1973年   6篇
  1968年   1篇
  1965年   1篇
排序方式: 共有2277条查询结果,搜索用时 15 毫秒
1.

Background

Treatment of advanced anal squamous cell cancer (SCC) is usually with the combination of cisplatin and 5-fluorouracil, which is associated with heterogeneous responses across patients and significant toxicity. We examined the safety and efficacy of a modified schedule, FOLFCIS (leucovorin, fluorouracil, and cisplatin), and performed an integrated clinical and genomic analysis of anal SCC.

Patients and Methods

We reviewed all patients with advanced anal SCC receiving first-line FOLFCIS chemotherapy – essentially a FOLFOX (leucovorin, fluorouracil, and oxaliplatin) schedule with cisplatin substituted for oxaliplatin – in our institution between 2007 and 2017, and performed deep sequencing to identify genomic markers of response and key genomic drivers.

Results

Fifty-three patients with advanced anal SCC (48 metastatic; 5 unresectable, locally advanced) received first-line FOLFCIS during this period; all were platinum-naive. The response rate was 48% (95% confidence interval [CI], 32.6%-63%). With a median follow-up of 41.6 months, progression-free survival and overall survival were 7.1 months (95% CI, 4.4-8.6 months) and 22.1 months (95% CI, 16.9-28.1 months), respectively. Among all patients with advanced anal SCC that underwent sequencing during the study period, the most frequent genomic alterations consisted of chromosome 3q amplification (51%) and mutations in PIK3CA (29%) and KMT2D (22%). No genomic alteration correlated with response to platinum-containing treatment. Although there were few cases, patients with human papillomavirus-negative anal SCC did not appear to benefit from FOLFCIS, and all harbored distinct genomic profiles with TP53, TERT promoter, and CDKN2A mutations.

Conclusions

FOLFCIS appears effective and safe as first-line chemotherapy in patients with advanced anal SCC and represents an alternative treatment option for these patients.  相似文献   
2.
Although classified by the Joint Monitoring Programme (JMP) as unimproved sanitation facilities, public toilets still play a critical role in eliminating open defecation in informal settlements. We explored perspectives of toilet operators on opportunities and barriers to operation and maintenance (O&M) of public toilets in informal settlements. A cross-sectional study design was used. Up to 20 in-depth interviews were used to obtain data on the experiences of public toilet operators. Thematic content analysis was used.

Ressults show that opportunities for improving O&M include; operation of public toilets is a source of livelihood; operators are knowledgeable on occupational risks, and the community is involvedin sanitation activities. Barriers to effective O&M include; high operation costs, failure to break even and a lack of investments in occupational health Therefore, there is need to recognise the significance of public toilets as a viable alternative to open defecation in areas where ownership of private sanitation facilities is difficult. Failure to observe the health and safety of toilet operators may further compromise O&M.  相似文献   

3.
SUMMARY A young patient presenting with splenomegaly and hypersplenism was inadvertently found to have selective IgA deficiency. There were no symptoms of immunodeficiency and the patient responded well to splenectomy, with return of blood counts to normal without adverse effects. No other cause for the hypersplenism was found. We postulate selective IgA deficiency as a cause of splenomegaly and hypersplenism.  相似文献   
4.
Oxygen free radicals generated during the reperfusion of an ischemic organ may cause further cellular injury; removal of these oxygen radicals by scavengers protects tissue from reperfusion injury. Thus, oxygen radical scavengers could protect kidneys after warm ischemia and long hypothermic perfusion. Porcine kidneys were incubated at 37 degrees C for 45 minutes, placed on a pulsatile perfusion apparatus at 7 degrees C for 48 hours, and then autografted to iliac vessels. Superoxide dismutase (10 mg) and catalase (10 mg) in 10 mL of phosphate-buffered saline solution were infused into the renal artery during a three-minute interval before reperfusion. The kidneys treated with the superoxide dismutase-catalase solution had significantly improved function compared with controls receiving only phosphate-buffered saline solution. The mean (+/- SEM) serum creatinine level on postoperative day 5 was 510 +/- 100 mumol/L (5.75 +/- 1.12 mg/dL) (n = 12) vs the control value of 840 +/- 90 mumol/L (9.54 +/- 1.01 mg/dL) (n = 11). There was more extensive cellular damage in the control kidneys. This demonstrates the efficacy of oxygen radical scavengers in protecting pig kidneys after warm ischemia and prolonged preservation.  相似文献   
5.
Immunotherapy requiring an efficient T lymphocyte response is initiated by antigen delivery to antigen-presenting cells. Several studies have assessed the efficiency of various antigen loading procedures, including microbial vectors. Here a live strain of Pseudomonas aeruginosa was engineered to translocate a recombinant antigenic protein into mammalian cells via the type III secretion system, a bacterial device translocating effector proteins into host cells. Optimization of the vector included virulence attenuation and determination of the N-terminal sequence allowing translocation of fused antigens into cells. In vitro delivery of an ovalbumin fragment by the bacterial vector into dendritic cells induced the activation of ovalbumin-specific CD8(+) T lymphocytes. Mice injected with the ovalbumin-delivering vector developed ovalbumin-specific CD8(+) T lymphocytes and were resistant to a subsequent challenge with an ovalbumin-expressing melanoma. Moreover, in a curative assay, injection of the vaccine vector 5 and 12 days after tumor implantation led to a complete cure in five of six animals. These results highlight the utility of type III secretion system-based vectors for anti-tumor immunotherapy.  相似文献   
6.
7.
Bradykinin B1 receptors are exclusively expressed in inflamed tissues. For this reason, they have been related with the outcomes of several pathologies. Ischemia–reperfusion injury is caused by the activation of inflammatory and cytoprotective genes, such as macrophage chemoattractant protein-1 and heme oxygenase-1, respectively. This study was aimed to analyze the involvement of bradykinin B1 and B2 receptors (B1R and B2R) in tissue response after renal ischemia–reperfusion injury. For that, B1R (B1−/−), B2R (B2−/−) knockout animals and its control (wild-type mice, B1B2+/+) were subjected to renal bilateral ischemia, followed by 24, 48 and 120 h of reperfusion. At these time points, blood serum samples were collected for creatinine and urea dosages. Kidneys were harvested for histology and molecular analyses by real-time PCR. At 24 and 48 h of reperfusion, B1−/− group resulted in the lowest serum creatinine and urea levels, indicating less renal damage, which was proved by renal histology. Renal protection associated with B1−/− mice was also related with higher expression of HO-1 and lower expression of MCP-1. In conclusion, the absence of B1R had a protective role against inflammatory responses developed after renal ischemia–reperfusion injury.  相似文献   
8.
Elevations of epidermal growth factor (EGF) and Ca2+ concentrations in the wound site are associated with reepithelialization during wound healing. In addition, Ca2+ and EGF can both induce increases in matrix metalloproteinase‐9 (MMP‐9) synthesis. However, little is known about the interplay of these events in regulating the migration properties of primary keratinocytes on collagen I, the most abundant extracellular matrix component in the skin. We found that EGF stimulated both chemokinetic and chemotactic migration of primary keratinocytes on collagen I; however, MMP‐9 was required for EGF‐stimulated chemotaxis but not EGF‐stimulated chemokinesis. Calcium at 0.5 mM stimulated chemokinetic migration of keratinocytes. Together, Ca2+ and EGF stimulated higher levels of chemokinesis than either stimulus alone. Furthermore, Ca2+ could restore the ability of keratinocytes from MMP‐9 null mice to undergo EGF‐stimulated chemotaxis. The phosphatidylinositol‐3 kinase inhibitor LY294002 inhibited both EGF‐ and Ca2+‐stimulated chemokinetic migration. In contrast, the MEK inhibitor PD98059 blocked Ca2+‐ but not EGF‐stimulated chemokinetic migration of keratinocytes. A combination of PD98059 and LY294002 was required to inhibit Ca2+ enhancement of EGF‐stimulated migration completely. Calcium‐stimulated chemokinesis was completely blocked by either the protein kinase C‐α inhibitor Gö6976 or the src/fyn inhibitor PP2. Using primary keratinocytes, our results showed how the combined action of Ca2+, EGF, and MMP‐9 regulated the contributions of extracellular‐regulated kinase and phosphatidylinositol‐3 kinase toward chemokinetic and chemotactic migration of keratinocytes.  相似文献   
9.
Bosco D  Mason G  Accotto GP 《Virology》2004,323(2):276-283
The transovarial transmission of two species of begomovirus, Tomato yellow leaf curl virus (TYLCV) and Tomato yellow leaf curl Sardinia virus (TYLCSV), through generations of Bemisia tabaci of the B and Q biotypes has been investigated. Different life stages of the progeny of viruliferous female whiteflies have been analysed by PCR detection of viral DNA and infectivity tests. Our results indicate that TYLCSV DNA can be detected in eggs and nymphs, and to a lesser extent adults, of the first-generation progeny. Infectivity tests using a large number of adult progeny of the first, second, and third generation indicate that even when viral DNA is inherited, infectivity is not. For TYLCV, neither viral DNA nor infectivity were associated with the progeny of viruliferous female whiteflies. Because the inherited viral DNA is unable to give rise to infections, the transovarial transmission of TYLCSV DNA appears to have no epidemiological relevance.  相似文献   
10.
Primitive Neuroectodermal Tumors of the Central Nervous System   总被引:2,自引:0,他引:2  
Controversial issues relating to the pathobiology and classification of central nervous system primitive neuroectodermal tumors (PNETs) have plagued neuropathologists for more than 70 years. Hypotheses advanced in the mid-1920's have remained as fixed concepts in contemporary literature, largely consequent to repetitious support by a small number of neuropathologists despite a growing body of information discrediting these ideas from neuroembryologists, oncologists, neuroscien-tists and pathologists.
Attention has largely focused upon PNETs arising in the cerebellum (commonly known as medul-loblastomas [MBs]), because about 80% of central nervous system (CNS) PNETs originate in this site. It has been asserted that the 20% which do not are biologically different, although most individuals agree that the histological features of PNETs that occur in different sites throughout the CNS are indistinguishable from those growing in the cerebellum.
The historical aspects of this controversy are examined in the face of evidence that there is, in fact, a unique class of CNS tumors which should appropriately be regarded as primitive neuroectodermal in nature. Specifically, a number of different approaches to the problem have yielded data supporting this hypothesis. These approaches include the identification of patterns of expression among a variety of cellular antigens (demonstrated by the use of immunopathological techniques), molecular analyses of cell lines derived from these tumors, experimental production of PNETs and molecular genetic analyses.
Differences of opinion among surgeons, oncologists and radiotherapists are typically resolved by conducting cooperative studies of patients with these tumors who are diagnosed and treated at multiple centers.  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