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   8356篇
  免费   545篇
  国内免费   40篇
耳鼻咽喉   107篇
儿科学   482篇
妇产科学   136篇
基础医学   1148篇
口腔科学   272篇
临床医学   550篇
内科学   1970篇
皮肤病学   195篇
神经病学   742篇
特种医学   521篇
外科学   1031篇
综合类   44篇
一般理论   1篇
预防医学   670篇
眼科学   104篇
药学   460篇
  1篇
中国医学   21篇
肿瘤学   486篇
  2023年   36篇
  2022年   72篇
  2021年   177篇
  2020年   94篇
  2019年   209篇
  2018年   238篇
  2017年   155篇
  2016年   134篇
  2015年   180篇
  2014年   218篇
  2013年   281篇
  2012年   394篇
  2011年   424篇
  2010年   276篇
  2009年   327篇
  2008年   391篇
  2007年   419篇
  2006年   427篇
  2005年   428篇
  2004年   395篇
  2003年   412篇
  2002年   338篇
  2001年   283篇
  2000年   301篇
  1999年   271篇
  1998年   168篇
  1997年   170篇
  1996年   170篇
  1995年   111篇
  1994年   106篇
  1993年   130篇
  1992年   137篇
  1991年   102篇
  1990年   99篇
  1989年   107篇
  1988年   85篇
  1987年   70篇
  1986年   73篇
  1985年   72篇
  1984年   52篇
  1983年   37篇
  1982年   35篇
  1981年   43篇
  1980年   29篇
  1979年   31篇
  1978年   28篇
  1977年   31篇
  1976年   41篇
  1975年   27篇
  1973年   19篇
排序方式: 共有8941条查询结果,搜索用时 15 毫秒
51.
We report 15 cases of spontaneous retroperitoneal haematoma. The etiology and the diagnostic and therapeutic procedures were evaluated. The haematoma source was the adrenal gland in 4 patients and the causes were pheochromocytoma (1), adenoma (1), myelolipoma (1) and idiopathic (1). In 10 patients the source was the kidney and the causes were angiomyolipoma rupture (6), renal cell carcinoma (3) and ureteral calculi (1). In the remaining case, the haematoma was produced by fibrinolytic and anticoagulant therapy in a patient with acute myocardial infarction. The imaging diagnostic techniques employed were abdominal ultrasonography and CT scan, which allowed the diagnosis of haematoma and showed his size and extension in all the cases. With these two techniques, and with the retrograde pyelography in one patient, we obtained the etiologic diagnosis in 12 of the 15 cases. Surgical treatment was performed in 12 patients (adrenalectomy in 2, simple nephrectomy in 3, radical nephrectomy in 5 and partial nephrectomy in 2).  相似文献   
52.
53.
54.
The congenital absence of the portal vein is a rare malformation, which has been generally discovered in association with another anomalies like a cardiac, gastrointestinal or genitourinary defects. With portal hypertension and hepatic cirrhosis, this anomaly is similar to spontaneous porto-systemic derivation, and for that not collateral venous drainage is present. In these patients, total interruption of mesentaric venous drainage during procurement of liver transplant produce a very important bowel and mesenteric edema, which can promote an injert fatal evolution. The authors present the first paediatric liver transplant, in a patient with portal venous agenesia, with de piggy-back technique was done and this complication was obviated, and a review of the literature about this issue is done.  相似文献   
55.
56.
57.
Improved immunogenicity of a core-coated tetanus toxoid delivery system.   总被引:2,自引:0,他引:2  
A new microparticulate delivery system composed of a stabilizing gelatin/poloxamer microcore surrounded by a PLGA coat was designed to improve the stability of tetanus toxoid (TT) encapsulated in PLGA microspheres. Microcores were prepared by a spray-congealing technique and encapsulated within PLGA using an oil-in-oil (o/o) solvent evaporation technique. SEM analysis of the cross-sections of the microcapsules revealed the adequate encapsulation of the cores, showing an intimate contact between the core and the coating. This structure was responsible for an osmotic phenomenon observed in vitro, which led to the release of the encapsulated TT in a short period of time. Nevertheless, it was observed that the release was affected by the presence of the poloxamer in the core: microspheres without poloxamer in the core exhibit a faster release (2 h) than those that incorporate the surfactant (24 h). The in vivo evaluation of this system showed that the encapsulated toxoid induced a low but continuous levels of neutralizing antibodies (Nt), whereas those obtained for the control (aluminum phosphate-adsorbed toxoid) decreased after reaching the maximum level at 14 weeks. Moreover, the administration of a mixture of encapsulated and adsorbed TT led to significant higher and more prolonged Nt levels than those measured for the adsorbed toxoid.  相似文献   
58.
59.
The reaction of platinum salts with bis(naphthalimide), compound 1, yielded two Pt-bis(naphthalimide) complexes, compounds 2 and 3 which differ from each other in their leaving groups being 1,1-cyclobutane dicarboxylate or chloride, respectively. The testing of the cytotoxic activity of compounds 2 and 3 against several tumor cell lines indicated that both compounds may be endowed with important antineoplastic properties since they circumvent cisplatin resistance. At similar rates of DNA platination (r(b) = 0.025), compounds 2 and 3 unwind supercoiled pUC8 DNA by (48 +/- 2) degrees. Altogether, these data suggest (i) that the cytotoxic activity of compounds 2 and 3 may be due to a combined effect of platination and intercalation and (ii) that the bis(naphthalimide) ligand is a suitable "carrier" that favors DNA targeting by cis-Pt(II) centers.  相似文献   
60.
The aim of the present study was to evaluate the influence of aluminium and iron on the in vitro dissolution kinetics of ciprofloxacin and ofloxacin as well as the usefulness of this type of in vitro data to predict modifications in in vivo absorption processes as a consequence of different factors, such as the widely documented in vivo interaction between quinolones and cations. Fitting of experimental data to different theoretical in vitro dissolution profiles was performed by non-linear regression methods and the statistical moments were calculated from raw experimental data. Analysis of residuals applied to dissolution curves as well as statistical comparison of the estimated parameters were carried out to evaluate the in vitro interaction. The results reveal significative modifications of the dissolution profiles of these quinolones as a consequence of the presence of cations, especially for Fe2+ which decreases 34.7% the maximum amount dissolved for ciprofloxacin and 29.1% for ofloxacin. Al3+ also produces a decrease of the total amount of quinolone dissolved although less relevant than Fe2+. Analysis of residuals proved to be the best statistical method to evaluate differences between whole dissolution profiles, at least under the experimental conditions used.  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