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   2155篇
  免费   194篇
  国内免费   45篇
耳鼻咽喉   2篇
儿科学   88篇
妇产科学   20篇
基础医学   312篇
口腔科学   40篇
临床医学   287篇
内科学   535篇
皮肤病学   14篇
神经病学   197篇
特种医学   185篇
外国民族医学   1篇
外科学   201篇
综合类   43篇
一般理论   2篇
预防医学   197篇
眼科学   47篇
药学   160篇
中国医学   1篇
肿瘤学   62篇
  2019年   25篇
  2018年   21篇
  2017年   17篇
  2016年   25篇
  2015年   23篇
  2014年   49篇
  2013年   50篇
  2012年   78篇
  2011年   66篇
  2010年   54篇
  2009年   60篇
  2008年   68篇
  2007年   114篇
  2006年   72篇
  2005年   86篇
  2004年   91篇
  2003年   79篇
  2002年   73篇
  2001年   58篇
  2000年   63篇
  1999年   60篇
  1998年   55篇
  1997年   43篇
  1996年   51篇
  1995年   34篇
  1994年   22篇
  1993年   30篇
  1992年   64篇
  1991年   53篇
  1990年   60篇
  1989年   65篇
  1988年   75篇
  1987年   61篇
  1986年   61篇
  1985年   34篇
  1984年   23篇
  1983年   32篇
  1982年   22篇
  1981年   17篇
  1980年   18篇
  1979年   23篇
  1978年   18篇
  1977年   28篇
  1976年   22篇
  1975年   22篇
  1974年   21篇
  1973年   16篇
  1972年   21篇
  1971年   23篇
  1970年   16篇
排序方式: 共有2394条查询结果,搜索用时 31 毫秒
1.
2.
Ultrasound cystography in the diagnosis of vesicoureteric reflux   总被引:5,自引:0,他引:5  
Vesicoureteric reflux is common in children with urinary tract infection and may cause end-stage renal failure. The diagnosis is usually based on micturating cystourethrography (MCU). We describe an alternative technique using ultrasound during bladder infusion with agitated saline. Comparison of the 2 methods shows ultrasound to be 100% sensitive in the detection of grades 3 and 4 reflux. Conclusive evidence of reflux was seen in 2 cases where MCU was subsequently normal, questioning the role of MCU as the gold standard.  相似文献   
3.
Studies were undertaken to define the expression of cytokeratins in normal, hyperplastic and malignant epithelial cells from human prostate. Cytokeratin (CK) polypeptides, separated by two-dimensional electrophoresis, were identified by immunoblotting with CK-specific monoclonal antibodies. CK polypeptides 5, 7, 8, 15, 18 and 19 were identified in fresh normal and hyperplastic prostate. Expression of CK 15 has not been previously reported in human prostate. Analysis of central and peripheral zone tissues from human prostate did not reveal qualitative differences in CK expression between these areas. Epithelial cells harvested from fresh BPH tissue by percoll gradient centrifugation and propagated in vitro using selective culture techniques showed alterations in CK expression compared to intact human prostate. Specifically, CKs 6, 14, 16 and 17 were noted in cultured BPH epithelial cells but not fresh normal prostate or BPH tissue. Immunoblot analysis of the established prostate cancer cell lines PC3, DU145 and LNCAP showed expression of CKs 8 and 18 but not CKs 5, 7 and 15 which were observed in benign prostate. These studies further characterize CK expression in benign and malignant human prostate and provide insights which may be useful in differentiating normal, hyperplastic and malignant epithelial cells in the human prostate gland.  相似文献   
4.
5.
(1) Liver cirrhosis was induced in male rats by treatment with carbon tetrachloride and phenobarbitone for 130-142 days. Detailed histological examination showed all livers from rats treated with carbon tetrachloride had annular fibrosis, necrosis, loss of normal hepatic architecture and other features that were consistent with an established micronodular cirrhosis. (2) Plasma biochemical analysis showed a significant reduction in total protein concentration (13%), which was due entirely to a reduction in plasma albumin (29%). There were also large increases in the plasma activities of alkaline phosphatase (110%) and aspartate aminotransferase (159%), when compared to phenobarbitone-treated controls. Plasma cholesterol was also increased (67%), but other plasma analytes were not significantly altered. (3) The soleus (Type I), plantaris (Type II) and gastrocnemius (Types I and II) muscles were dissected and examined for possible differential effects. There were minor reductions in all three muscle weights, but these changes did not reach statistical significance. The protein, RNA and DNA concentrations, total muscle content and content relative to body weight in cirrhotic rats were also not significantly altered in any of the muscles. Cirrhosis did not cause any perturbations in derived parameters, i.e. amount of synthetic apparatus per cell, RNA/DNA ratio, apparent cell size, protein/DNA ratio and the capacity for protein synthesis or RNA/protein ratio. (4) The gastrocnemius was fractionated into soluble, stromal and myofibrillar proteins. The concentrations and contents of all three proteins were unaltered in cirrhotic animals, compared to controls. (5) It is concluded that in this experimental model of cirrhosis there were no effects on those skeletal muscle variables which are strikingly altered by chronic alcohol feeding.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
6.
7.
8.
We used arthrotomography to study the glenoid labrum in 114 patients. Sixty-nine of the patients had anatomic instability of the shoulder (including recurrent dislocation and subluxation of the shoulder), and 45 patients had functional instability of the shoulder (denoted by chronic pain, clicking of the joint, and the sensation that an unstable condition exists without the objective signs of it). Labral tears were revealed arthrotomographically in 86% of the patients with anatomic instability, while only 40% of the patients with functional instability had labral abnormalities, and these were primarily of minor severity. Fifty-six patients (44 of whom had anatomic instability; 12, functional instability) required surgery. The surgical findings were correlated with the arthrotomographic findings, and no false-positive results were revealed. However, arthrotomography demonstrated only part of the pathologic condition of two patients. These results confirm that there is a strong correlation between labral pathologic conditions and anatomic instability of the shoulder. Arthrotomographic studies have a great impact on the selection of therapy in cases of both anatomic and functional instability of the shoulder.  相似文献   
9.
Ninety-two nonglaucomatous patients undergoing extracapsular cataract extraction with implantation of a posterior chamber intraocular lens by residents at a Veterans hospital were randomized in double-masked fashion to receive either a topical nonsteroidal antiinflammatory agent, diclofenac sodium 0.1%, or a placebo consisting of vehicle only. One drop of placebo or diclofenac sodium 0.1% was administered on an inpatient basis by trained staff every 6 hours for three doses, starting the afternoon prior to surgery. A further drop was given at 90, 60, 30, and 15 minutes before the operation. Starting 24 hours after surgery, all patients received diclofenac sodium 0.1%. All patients remained hospitalized for 72 hours postoperatively. Mean baseline intraocular pressure (IOP) was 14.0 and 14.1 mm Hg in the diclofenac and placebo groups, respectively. IOP rose 8.6 mm Hg in both groups at 6 hours after surgery. At 24 hours, the mean IOP elevation from baseline was 11.3 mm Hg in the diclofenac group and 9.6 mm Hg in the placebo group (P = .47). Within the first 24 hours, IOP spiked more than 10 mm Hg in 57% (26/46) of the diclofenac patients and in 54% (25/46) of the placebo patients. These results suggest that diclofenac sodium 0.1% drops affect neither the incidence nor the height of IOP elevation following cataract surgery.  相似文献   
10.
A nitroreductase enzyme that has been isolated from Escherichia coli B is capable of bioactivating CB1954 [5-(aziridin-1-yl)-2,4-dinitrobenzamide] to a cytotoxic agent, a property shared with the mammalian enzyme Walker DT diaphorase [NAD(P)H dehydrogenase (quinone), EC 1.6.99.2] as isolated from Walker cells. In contrast to Walker DT diaphorase, which can only reduce the 4-nitro group of CB1954, the E. coli nitroreductase can reduce either (but not both) nitro groups of CB1954 to the corresponding hydroxylamino species. The two hydroxylamino species are formed in equal proportions and at the same rates. CB1954 is reduced much more rapidly by the E. coli nitroreductase than by Walker DT diaphorase. If the reduction of CB1954 was carried out in the presence of V79 cells (which are insensitive to CB1954) a large cytotoxic effect was evident. This cytotoxicity was only observed under conditions in which the E. coli nitroreductase or Walker DT diaphorase reduced the drug. It is proposed that E. coli B nitroreductase would be a suitable enzyme for antibody-directed enzyme prodrug therapy (ADEPT) in combination with CB1954.  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