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   1441篇
  免费   102篇
  国内免费   2篇
耳鼻咽喉   5篇
儿科学   50篇
妇产科学   55篇
基础医学   193篇
口腔科学   127篇
临床医学   85篇
内科学   223篇
皮肤病学   20篇
神经病学   55篇
特种医学   33篇
外科学   259篇
综合类   29篇
一般理论   1篇
预防医学   88篇
眼科学   99篇
药学   87篇
中国医学   8篇
肿瘤学   128篇
  2023年   13篇
  2022年   19篇
  2021年   52篇
  2020年   23篇
  2019年   24篇
  2018年   45篇
  2017年   26篇
  2016年   43篇
  2015年   32篇
  2014年   64篇
  2013年   73篇
  2012年   103篇
  2011年   88篇
  2010年   53篇
  2009年   47篇
  2008年   71篇
  2007年   63篇
  2006年   74篇
  2005年   67篇
  2004年   61篇
  2003年   45篇
  2002年   43篇
  2001年   26篇
  2000年   33篇
  1999年   23篇
  1998年   10篇
  1997年   10篇
  1996年   11篇
  1995年   13篇
  1994年   7篇
  1992年   12篇
  1991年   24篇
  1990年   13篇
  1989年   24篇
  1988年   16篇
  1987年   18篇
  1986年   24篇
  1985年   11篇
  1984年   11篇
  1983年   13篇
  1977年   7篇
  1975年   6篇
  1974年   8篇
  1973年   8篇
  1972年   12篇
  1971年   6篇
  1970年   6篇
  1969年   8篇
  1968年   11篇
  1967年   6篇
排序方式: 共有1545条查询结果,搜索用时 203 毫秒
31.
32.
A series of new 5-aryliden-2-imino-4-thiazolidinones (5ae and 6ae) were synthesized via a three-step reaction and characterized by physicochemical and spectral data. The uniqueness of the derivatives lies in the fact that none of them had an acidic group, like conventional NSAIDS, but exhibited significant in vivo activity in acute inflammation models. In particular, 5-(3-chlorobenzyliden)-2-(pyridin-2-yl-imino)-4-thiazolidinone(5a) and 5-(3-chlorobenzyliden)-2-(5-methylisoxazol-3-yl-imino)-4-thiazolidinone (6a) showed remarkable paw oedema inhibition (67.76 and 74.47 % oedema inhibition, respectively, after 3 h) comparable to that of Ibuprofen (74.56 % oedema inhibition, after 3 h) at half of the dose of the standard drug. Also, compounds 5a (72.86 %) and 6a (80.20 %) were found to possess significant inhibition of albumin denaturation when screened for in vitro anti-inflammatory activity. In addition, these compounds were docked into the known active site of COX-2 protein using Glide XP and QPLD algorithms, and the binding-free energy was calculated using Prime MM/GBSA simulation methods. The combined use of molecular docking and MM/GBSA methods gave a good correlation between the predicted binding-free energy and experimentally determined biological activities. It was also evident from the docking results that 2-methylisoxazolylimino or 2-(pyridin-2-yl-imino substitution and 3-chloro moiety on 5-benzylidin nucleus of these 4-thiazolidinone derivatives can easily occupy the COX-2 binding pocket, considered as the critical interaction for COX-2 inhibition. Moreover, pharmacokinetic properties of all the synthesized compounds were predicted, with good results. Further, the synthesized derivatives showed neither acute toxicity nor symptoms of gastric ulceration, at extended doses, owing to the absence of an acidic group.  相似文献   
33.
Chloride–bromide halogen exchange was realized when a mixture of an alkyl chloride and an alkyl bromide were reacted over a supported molten alkyl phosphonium catalyst. Conversion was found to be near equilibrium in a tubular flow reactor at 150 °C and 1500 GHSV. The catalyst was prepared by impregnation of alumina or silica support and found to be highly stable for relatively long periods of time. A pathway for the catalytic cycle is proposed.

Chloride–bromide halogen exchange was realized when a mixture of an alkyl chloride and an alkyl bromide were reacted over a supported molten alkyl phosphonium catalyst.  相似文献   
34.
Background: Gastrointestinal specialists depend on internal medicine (IM) teams to accurately identify acute gastrointestinal bleeding (GIB). We evaluated whether IM residents’ assessment of GIB correlated with the impressions of GI specialists during consultations at an inner-city university teaching hospital. Methods: A questionnaire was distributed to house staff requesting GIB consultations and to the GI fellows performing the consults between August 2011 and April 2012. Residents and fellows were asked to assess GIB, specifically melena, using a stool color card and digital rectal examination (DRE) findings. Fellow DRE findings served as controls for stool color identification. Results: Eighty-seven GI consults were eligible for the study. Residents and fellows completed 81 and 86 questionnaires, respectively. A total of 76 questionnaires were included for analysis. A DRE was performed by medical staff before calling a consult in 65% of cases compared with fellows (97% of cases, P = 0.0001). Residents more frequently labeled stool as melena (42%) in patients as compared with fellows (12%, P = 0.0001). Residents inaccurately identified melenic stools in 22 patients (11 based on stool color and 11 based on DRE findings). Residents were more likely to label a consult as emergent than fellows (13.5% vs 4%, P < 0.05). Conclusion: Residents are less likely to perform DRE during an evaluation for GIB and to accurately identify melena based on stool color or DRE findings. There appears to be a need to educate residents on the appropriate terminology for stool color and the importance of DRE to accurately triage patients with acute GIBs.  相似文献   
35.
36.
Equine herpesvirus-1 (EHV-1) strains with a single point mutation at the 2254 nucleotide position with a G2254 constitution within the DNA polymerase gene are associated strongly with equine myeloencephalopathies. Infections with non-neuropathogenic EHV-1 strains without the G2254 nucleotide but with an A2254 nucleotide are associated less frequently with equine neurologic disease. A retrospective study utilizing DNA extracted from formalin fixed paraffin embedded tissues was conducted with real time PCR and pyrosequencing, to determine the infecting EHV-1 strains. Infection with EHV-1 A2254 and or G2254 strain was detected with real time PCR, and was confirmed with a rapid pyrosequencing technique. Pyrosequencing was useful in at least 2 cases where real time PCR was equivocal in determining the infecting EHV-1 strain type. The strain with G2254 mutation was detected in 9.4% of 21 studied abortion cases, and in 86.6% of 15 neurologic cases.  相似文献   
37.
38.
Kidney tumors of various types may behave differently and have different prognosis. Because of some overlapping morphological features and immunohistochemical staining pattern, they may pose diagnostic challenge. Therefore, it is necessary to explore additional immunohistochemical stains to help classifying these epithelial neoplasms. Tissue microarrays of 20 cases each of renal cell carcinomas of clear cell, chromophobe, and papillary variants and oncocytoma were constructed and used to test a panel of immunohistochemical markers including carbonic anhydrase IX, galectin-3, cytokeratin 7 (CK7), and α-methylacyl coenzyme a racemase. Carbonic anhydrase IX was highly sensitive for clear cell renal cell carcinoma (90% positivity) and was negative in all other renal epithelial tumors except for 1 chromophobe renal cell carcinoma (chRCC). Expression of galectin-3 was found mostly in renal tumors with oncocytic features, including oncocytomas (100%) and chRCCs (89%). α-Methylacyl coenzyme a racemase was positive in papillary renal cell carcinoma (100%). CK7 was positive in papillary renal cell carcinoma (90%), chRCC (89%), and oncocytoma (90%). Although both chRCC and oncocytoma were positive for CK7, but with a different patterns, CK7 staining in chRCC was diffuse, whereas it was sporadic in oncocytoma. Panel of carbonic anhydrase IX, galectin-3, CK7, and α-methylacyl coenzyme a racemase is sensitive and specific for the differential diagnosis of the renal epithelial tumors.  相似文献   
39.
40.

Background:

Many authors have reported the anatomical variation of abductor pollicis longus (APL) around the wrist and its association with de Quervain tenosynovitis (DQT), first carpo-metacarpal arthritis, and trapezio-metacarpal subluxation. From Indian subcontinent, there is only one original article and a few case reports on the variability of APL tendon insertion.

Materials and Methods:

Fifty formaldehyde preserved cadaveric wrists were dissected to look for the anatomical variation of APL in the Indian population.

Results:

The APL was found with single tendon in 2, double in 31, triple in 8, and quadruple in 8 extremities. A maximum of 6 tendon-slips were found in one cadaveric wrist. In all hands, the APL had at least one attachment to first metacarpal bone and in 46 hands (92%), there was second insertion to the trapezium bone. Of all tendon-slips of APL (n = 126), 44% of tendons (68 tendons) were inserted into the base of the first metacarpal bone. This was followed by the insertion into the trapezium in 42% tendons (52 tendons).

Conclusion:

Bi-tendinous APL is commonly observed on the dorsal compartment of the wrist in Indian population and these tendon-slips are commonly attached to the first metacarpal base and trapezium. This variation must be understood by the Indian Orthopedic surgeons as the response to treatment of DQT and reason for first carpo-metacarpal arthritis can be dependent on this anatomical variation.  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