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   931954篇
  免费   66421篇
  国内免费   1343篇
耳鼻咽喉   12958篇
儿科学   24361篇
妇产科学   23242篇
基础医学   132886篇
口腔科学   28246篇
临床医学   80534篇
内科学   183303篇
皮肤病学   19226篇
神经病学   72168篇
特种医学   36799篇
外国民族医学   79篇
外科学   152164篇
综合类   18044篇
现状与发展   1篇
一般理论   234篇
预防医学   61736篇
眼科学   21308篇
药学   72523篇
  3篇
中国医学   2162篇
肿瘤学   57741篇
  2018年   8964篇
  2017年   7029篇
  2016年   7760篇
  2015年   8860篇
  2014年   11985篇
  2013年   17495篇
  2012年   24081篇
  2011年   25029篇
  2010年   14801篇
  2009年   14265篇
  2008年   24608篇
  2007年   25703篇
  2006年   26503篇
  2005年   25438篇
  2004年   24568篇
  2003年   23613篇
  2002年   23164篇
  2001年   54731篇
  2000年   56549篇
  1999年   46953篇
  1998年   10741篇
  1997年   9471篇
  1996年   9599篇
  1995年   8930篇
  1994年   8283篇
  1993年   7596篇
  1992年   35489篇
  1991年   33916篇
  1990年   32734篇
  1989年   31870篇
  1988年   28992篇
  1987年   28249篇
  1986年   26288篇
  1985年   25144篇
  1984年   17832篇
  1983年   15141篇
  1982年   7795篇
  1981年   6771篇
  1979年   15781篇
  1978年   10598篇
  1977年   9052篇
  1976年   7871篇
  1975年   8628篇
  1974年   10466篇
  1973年   9858篇
  1972年   9357篇
  1971年   8852篇
  1970年   8426篇
  1969年   7923篇
  1968年   7200篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
A prognosis of patients with a curative resected advanced cancer of the lower gastric region was worse than that of the other region of the stomach. The 5 year survival rate was only 47.3%. One of the main reasons was that a rate of lymph node recurrence was higher. In this point of view, we studied on lymphatic flow of the lower gastric region using an activated carbon particle (CH40). Lymph nodes were stained black soon after the injection of CH40 into the lower gastric wall at laparotomy. The black stained rate of an each regional lymph node was as follows. 3. 58%, 4. 17%, 5. 50%, 6. 25%, 1. 21%, 7. 58%, 8. 83%, 9. 58%, 11. 17% and 12. 33% in case of injection into the greater curvature and and 4. 31%, 6. 100%, 8. 25%, 9. 25%, 14V and 56% in case of injection into the lesser curvature. The stained rate was relatively high in 12 and 14V lymph node which we had not routinely dissected. The rates of lymph nodes stained black were related to those of cancer metastasis. The results suggest that lymphadenectomy of 12 for the cancer at the lesser curvature and that of 14V for the cancer at the greater curvature might make a prognosis of lower gastric cancer better.  相似文献   
72.
The present study evaluates the response comparability between 361 elderly hip fracture patients admitted from the community to seven Baltimore area hospitals between 1984 and 1986 and interviewer selected proxies on items pertaining to patients' pre-fracture health and functional status. Agreement across items ranges from very poor to good and varies with respect to the health or functional area assessed. Proxies tend to overestimate patient disability relative to the patients themselves, especially with regard to capacity to perform instrumental activities of daily living. Although proxies who report the greatest contact with patients respond most comparably to the patients, when they do disagree, proxies with the greatest patient contact tend to overestimate patient disability. The authors suggest that attention to item construction and phrasing may improve response comparability.  相似文献   
73.
Correlation studies were performed relating iron availability estimated in vitro using a simulated digestion system to the concentration of protein, sugar, fibre, phytate, ascorbate and citrate in 33 different plant foods. Protein, sugar and fibre showed no significant correlation with iron availability. Phytate was significantly negatively correlated with diffusible iron in cereals, legumes and nuts. Both ascorbate and citrate were highly positively correlated with diffusible iron in vegetables and fruits. It is concluded that iron availability may be related on a quantitative basis to certain components of plant foods.  相似文献   
74.
The biodistribution of two recently developed tumour markers, trimethylated (CP(Me)3) and trimethoxylated (CP(OMe)3) carotenoporphyrin, was investigated by means of laser-induced fluorescence (LIF) after i.v. injection into 38 tumour-bearing (MS-2 fibrosarcoma) female Balb/c mice. At 3, 24, 48 or 96 h after administration, the carotenoporphyrin fluorescence was measured in tumoral and peritumoral tissue, as well as in the abdominal, thoracic and cranial cavities. The fluorescence was induced by a nitrogen laser-pumped dye laser, emitting light at 425 nm, and analysed by a polychromator equipped with an image-intensified CCD camera. The fluorescence was evaluated at 490, 655 and 720 nm: the second and third wavelengths represent the carotenoporphyrin (CP)-related peaks, whereas the first one is close to the peak of the tissue autofluorescence. The tumour and the liver were the two tissue types showing the strongest carotenoporphyrin-related fluorescence, whereas the cerebral cortex and muscle consistently exhibited weak substance-related fluorescence. In most tissue types, the fluorescence intensities decreased over time. A few exceptions were observed, notably the liver, in which the intensity remained remarkably constant over the time period investigated.  相似文献   
75.
Psychometric data are presented which examine the validity of using the concentration of benzoylecgonine in urine, a major metabolite of cocaine, as a measure of drug use, in studies of drug abuse treatments. In such research the standard biological indicator of drug use is usually a qualitative urine drug test, which merely indicates the presence or absence of a drug or its metabolite. A quantitative (i.e. continuous) outcome measure, such as the concentration of a drug or its metabolite in a biological fluid, has substantially more statistical power than a dichotomous measure and should, therefore, prove a more sensitive measure of drug use when viewed from a measurement perspective. Data from two placebo-controlled clinical trials of fluoxetine as an adjunct to treatment for cocaine abuse are analyzed to address this issue. Results indicate that urine benzoylecgonine level is closely related to self-reports of drug use and is independent of levels of anxiety, depression and hopelessness.  相似文献   
76.
The results of the in vitro fertilisation programme at Tygerberg Hospital for the period April 1983 to January 1988 are presented. Of the 1117 laparoscopies performed, 825 patients reached the transfer stage. A live-birth rate of 9.3% was achieved. The pregnancy rate after transfer of 4 embryos was 25.9% compared with 15.4% after 2 embryos and 10.8% after 3 embryos (P = less than 0.0001). The multiple pregnancy rate was 2.8% in the group receiving 2 embryos and 11.7% and 10.4% in those receiving 3 and 4 embryos, respectively. Of the 77 successful pregnancies (90 babies), 1 baby died at 34 weeks' gestation as the result of abruptio placentae due to preeclampsia and 1 cot death occurred. The only congenital abnormality encountered was a cleft palate.  相似文献   
77.
Corpus cavernosography in a patient with erectile dysfunction revealed absence of communication between the 2 cavernous bodies. No similar case was found in a review of 100 consecutive cavernosograms or in the literature. The abnormality may be a source of error in pressure recordings or in intravenous injection of pharmaceutical agents.  相似文献   
78.
Gallstone dissolution   总被引:2,自引:0,他引:2  
Many methods are available for gallstone dissolution, including oral bile salts; cholesterol solvents such as mono-octanoin or methyl tert-butyl either; and calcium or pigment solvents such as EDTA and polysorbate. Which of these approaches will be appropriate for an individual patient depends on the type of stones; whether they are in the gallbladder or the bile ducts; whether access to the biliary tree is available; the patient's age and general medical condition; and the availability of necessary expertise. In the US, both chenodeoxycholate and ursodeoxycholate are now available. Ursodeoxycholate is more expensive but appears to produce fewer side effects and may be more efficacious. These agents are most effective in thin women with small floating, radiolucent cholesterol stones in a functioning gallbladder. Only about half of the small subset of patients will experience partial or complete dissolution of stones within a year. Stone recurrence and the potential toxicity of long-term therapy are problems with this approach. Therefore, for most patients, cholecystectomy, either in the traditional fashion or using a laparoscopic approach (see article later in this issue by Gadacz et al), is the most cost-effective and perhaps the safest option. Intragallbladder instillation of methyl tert-butyl ether probably will be applicable only to a small subset of patients, and treatment is likely to be followed by a high recurrence rate. In patients with retained common duct cholesterol stones and access to the biliary tree, mono-octanoin therapy is advantageous in that it can be initiated as soon as cholangiography demonstrates no extravasation. In properly selected patients, a 90% success rate with this technique can be expected within 7 days.  相似文献   
79.
Patients on long-term haemodialysis suffer from dialysis arthropathy due to the deposition of dialysis amyloid. We investigated the use of 99Tc-labelled methylene diphosphonate bone scans in 17 patients as a possible in vivo diagnostic technique. In most clinically affected joints, with the exception of shoulders and hands, there was increased radioisotope uptake consistent with uptake by periarticular bone. In addition, we describe intense soft-tissue uptake around some clinically affected large joints. In contrast, control groups of patients on haemodialysis without arthropathy and patients without renal failure did not have increased uptake. A semi-quantitative scale of uptake was devised, and the following correlations were significant: pain perception and isotope uptake score in the ankles and feet, and the number of radiological lesions and isotope uptake scores in the wrists and knees. The following sites where the radioisotope might bind in the affected joints are proposed: amyloid deposits, areas of soft-tissue calcification, or areas of increased bone turnover. It is concluded that whereas the scanning technique cannot make a definite diagnosis of amyloid and, therefore, cannot be expected to supersede histological diagnosis, it is a useful adjuvant investigation, of particular importance in those patients unable or unwilling to undergo biopsy.  相似文献   
80.
Eleven patients with lunatomalacia were treated by excision of the lunate and instillation of liquid silicone. The silicone vulcanised and formed an in-situ molded prosthesis. The patients were reexamined after a mean of 7.1 years. Four patients were pain-free and two had pain only at work; three had not been improved by the operation and two had undergone arthrodesis. The patients with good results all belonged to group IV pre-operatively. Surprisingly, no patient showed any sign of silicone synovitis, although all the prostheses except one had either fractured or deformed. The reasons for this are discussed and the indications for the operation established.  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