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   827篇
  免费   42篇
  国内免费   1篇
耳鼻咽喉   2篇
儿科学   19篇
妇产科学   14篇
基础医学   52篇
口腔科学   21篇
临床医学   188篇
内科学   195篇
皮肤病学   40篇
神经病学   35篇
特种医学   88篇
外国民族医学   1篇
外科学   59篇
综合类   37篇
一般理论   1篇
预防医学   31篇
眼科学   4篇
药学   47篇
中国医学   1篇
肿瘤学   35篇
  2022年   17篇
  2021年   13篇
  2020年   9篇
  2019年   14篇
  2018年   15篇
  2017年   15篇
  2016年   9篇
  2015年   15篇
  2014年   20篇
  2013年   28篇
  2012年   9篇
  2011年   18篇
  2010年   34篇
  2009年   29篇
  2008年   14篇
  2007年   15篇
  2006年   19篇
  2005年   13篇
  2004年   10篇
  2003年   17篇
  2002年   16篇
  2001年   8篇
  2000年   15篇
  1999年   14篇
  1998年   23篇
  1997年   13篇
  1996年   26篇
  1995年   21篇
  1994年   25篇
  1993年   31篇
  1992年   19篇
  1991年   12篇
  1990年   12篇
  1989年   27篇
  1988年   23篇
  1987年   15篇
  1986年   14篇
  1985年   19篇
  1984年   12篇
  1983年   15篇
  1982年   17篇
  1981年   13篇
  1980年   15篇
  1979年   13篇
  1978年   10篇
  1977年   10篇
  1975年   8篇
  1957年   9篇
  1949年   8篇
  1948年   8篇
排序方式: 共有870条查询结果,搜索用时 22 毫秒
41.
Summary Seventeen male manual metal-arc stainless steel welders (mean exposure time 20 years) had far higher levels of chromium in urine than individually matched controls (medians 23 vs 1.5 mol/mol creatinine;10.5 vs 0.7 g/g creatinine). However, there were no signs of kidney damage in tests of function of tubuli (-hexosaminidase, lysozyme, and 2-microglobuline) or glomeruli (albumine clearance).  相似文献   
42.
The aim was to explore experiences of daily occupations among the oldest old. Ten 99-year-old persons were interviewed in their living environment about an ordinary day. The interviews were analysed according to the phenomenographic approach. The result showed that participants regarded themselves as competent and that they felt proud because they were involved in daily occupations. Being challenged was experienced as a way of performing difficult tasks, thus being confirmed as a capable person who performs and learns new things. The participants' occupational patterns preserve occupational ability and continuity in life in that they have a rhythm and allow the individuals to predict and handle interruptions. Participants experienced being incapable and being restricted as a result of personal, environmental, and social hindrances. The participants adapted to and reshaped their sense of self, which has been disrupted due to the discrepancy between self, the person's ability, and the real world "outside". Experience of daily occupation is unique, supports the sense of self, builds identities, and describes engagement and creative processes. Individual experience must be recognized as it can mean the difference between success and failure in maintaining meaningful daily occupation.  相似文献   
43.
Summary. Haemophilia A is the most common inherited X‐linked recessive bleeding disorder. The aim was to investigate the usefulness of two DNA markers in linkage analysis, one intragenic BCL1 affecting restriction site in intron 18, and is detected as restriction fragment length polymorphism (RFLP), and one extragenic variable number of tandem repeat (VNTR) locus DXS52 (St14) to formulate an informative and accurate carrier detection and prenatal diagnosis. The study included 46 families with at least one child affected with haemophilia A, and 30 unrelated normal females as control group. Polymerase chain reaction (PCR) and restriction enzyme analysis were used to study the polymorphism in BCL1, and long‐distance PCR for detection of VNTR (ST14) alleles. The incidence of BCL1 (+) allele was 74%, 72% and 60% in patients, mothers and control group, respectively. Expected heterozygosity for BCL1 was 40% in mothers of affected cases compared with 48% in the female control group. However, observed heterozygosity was found to be 48% in the mothers of affected cases, compared with 60% in the control group. Thus, 48% of the studied families are informative for this marker alone. Nine different alleles of VNTR (St14) were observed in mothers and six alleles in affected cases and six in the control group. The most prevalent alleles were 1300 bp (45.5% and 34%) and 700 bp (13.6% and 20%) in patients and their mothers, respectively. Observed heterozygosity in mothers was 41% compared with 43.3% in controls. The combined use of both BCL1 and St14 markers raised the informative rate to 63.6%. Carrier detection and prenatal diagnosis is possible in haemophilia A families using both DNA markers. We suggest screening haemophilic families first for BCL1 polymorphism followed by analysis of St14 locus.  相似文献   
44.
Fifty-two immunocompromised patients with suspected septicaemia were randomized on 61 occasions to treatment with ceftazidime or with tobramycin and cefuroxime. Most (90%) of the patients had haematological malignancies and were neutropenic (granulocytes less than 1 X 10(9)/1 in 40 of the 61 episodes). Blood cultures were positive in 22 (39%) febrile episodes and in four other instances positive cultures were obtained from other sources. Clinical cure or improvement was noted in 10 of 12 culture verified infections in the tobramycin and cefuroxime group and 11 of 14 episodes in the ceftazidime-group. The effect on the kidney of the two antibiotic regimens was studied by following the serum levels of creatinine, urea and beta 2-microglobulin and the urinary excretion of alanine aminopeptidase, N-acetyl-beta-D-glucosaminidase (beta-NAG) and beta 2-microglobulin. No clinically important renal side effects were observed. However, an increase in the urinary excretion of AAP was seen in both groups with significantly greater elevation in the tobramycin and cefuroxime group. Urinary beta-NAG increased only in the tobramycin and cefuroxime group.  相似文献   
45.
46.
Wiener  JI; Chako  AC; Merten  CW; Gross  S; Coffey  EL; Stein  HL 《Radiology》1986,160(2):299-305
We tested a variety of inversion-recovery (IR) and spin-echo (SE) sequences by imaging the breast masses of 22 patients before surgery and 23 tissue specimens with magnetic resonance (MR) imaging at 0.6 T to determine the most effective pulse sequences to evaluate breast disease. An SE pulse sequence using a long repetition time (TR) of 1,600 msec and a long echo time (TE) of 90 msec was found to be the most sensitive in depicting carcinoma in the excised tissue specimens, with all of the carcinomas (n = 15) demonstrating irregular areas of higher signal intensity (SI) than that of the adjacent fat. However, only five of 11 breast carcinomas present in the preoperative patients produced a higher SI than that produced by fat on the same T2-weighted sequence. Five of the remaining six carcinomas in the preoperative patients appeared as localized distortions of fibroductular architecture on both T2-weighted SE and IR sequences. In axillary tissue specimens, both metastatic carcinoma and hyperplastic lymph nodes produced a high SI on T2-weighted SE sequences. However, metastatic carcinoma had a significantly longer T2 relaxation time than did hyperplastic lymph nodes.  相似文献   
47.
48.
The lysosomal enzyme beta-hexosaminidase and the melanocyte specific enzyme tyrosinase were examined in human melanoma cell cultures. The beta-hexosaminidase activity of the medium was approximately 40% of the total cellular activity after 24 h, while after 48 h the activity in the medium was twice that of the cells. The tyrosinase activity in the medium was 5% and 19% of the total cellular activity after the 24 h and 48 h incubation, respectively. The low level of lactate dehydrogenase activity in the medium after 24 as well as 48 h of incubation indicated that the release of beta-hexosaminidase and tyrosinase was not due to membrane injury. The data suggest, that 1) beta-hexosaminidase may be a candidate for tumor markers in malignant melanoma, and 2) the tyrosinase activity found in sera of melanoma patients may be due, at least partly, to enzyme release by living cancer cells.  相似文献   
49.
The influence of pacemaker output on the morphology of the paced QRS complex was studied from standard lead electrocardiograms in 69 patients with bipolar pacemakers. In 40 of the 69 patients (58%), there was a significant (P less than 0.001) change in electrical axis, from -75 degrees at the low output setting (2.7 V, 0.15 msec) to -67 degrees at the high output setting (8.1 V, 2.29 msec). In 30 patients, these changes were also associated with changes in the QRS morphology and in the T-wave. This phenomenon may be explained by additional stimulation from the proximal electrode at high output, thus altering the pattern of depolarization.  相似文献   
50.
Clinical use of white cell-poor blood components   总被引:1,自引:0,他引:1  
EL Snyder 《Transfusion》1989,29(7):568-571
  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