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   24249篇
  免费   1834篇
  国内免费   78篇
耳鼻咽喉   396篇
儿科学   842篇
妇产科学   401篇
基础医学   2494篇
口腔科学   540篇
临床医学   2185篇
内科学   5357篇
皮肤病学   555篇
神经病学   1354篇
特种医学   1115篇
外国民族医学   1篇
外科学   4565篇
综合类   345篇
一般理论   15篇
预防医学   1193篇
眼科学   842篇
药学   2108篇
中国医学   48篇
肿瘤学   1805篇
  2023年   227篇
  2022年   408篇
  2021年   1001篇
  2020年   478篇
  2019年   826篇
  2018年   964篇
  2017年   627篇
  2016年   669篇
  2015年   686篇
  2014年   1039篇
  2013年   1230篇
  2012年   1799篇
  2011年   1756篇
  2010年   905篇
  2009年   835篇
  2008年   1308篇
  2007年   1233篇
  2006年   1163篇
  2005年   1008篇
  2004年   909篇
  2003年   778篇
  2002年   672篇
  2001年   590篇
  2000年   559篇
  1999年   495篇
  1998年   164篇
  1997年   145篇
  1996年   140篇
  1995年   144篇
  1994年   113篇
  1993年   98篇
  1992年   270篇
  1991年   288篇
  1990年   248篇
  1989年   218篇
  1988年   209篇
  1987年   220篇
  1986年   193篇
  1985年   179篇
  1984年   113篇
  1983年   129篇
  1982年   87篇
  1981年   71篇
  1980年   63篇
  1979年   131篇
  1978年   77篇
  1977年   70篇
  1975年   60篇
  1974年   66篇
  1973年   89篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
Herniography has been used for 25 years in the diagnosis of occult herniation but has not gained widespread acceptance in the UK, despite studies confirming its high sensitivity and specificity for occult hernias and an excellent record of safety and patient acceptability. The traditional approach in the UK to suspected occult groin herniation has been surgical exploration. This study examined the use of herniography in a single district general hospital to assess its impact in limiting unnecessary groin explorations and allowing discharge of patients without hernias. The case notes of 90 successive patients referred for herniography by the department of general surgery in a single UK district general hospital over an 18-month period were reviewed. Eighty-seven completed examinations were analysed in which 23 hernias were diagnosed in 20 patients. Thirteen patients have undergone hernia repair with resolution of symptoms. There were no false positive examinations, although two inguinal hernias were incorrectly diagnosed radiologically as femoral hernias; there were two false negative examinations where additional hernias were found at laparoscopic repair. There were no reported complications. Twenty-four patients were discharged directly from the surgical clinic after a negative herniogram. Thirty patients were referred to other specialities. No patient had undergone groin exploration after a negative herniogram. Herniography is a useful tool in assessing obscure groin pain and potential occult herniation. It can reliably rule out the presence of a hernia and avoid the need for surgical exploration. Many patients with a negative herniogram can be reassured and discharged, whilst others may be referred on to other specialities safe in the knowledge that an occult hernia has been excluded.  相似文献   
3.
Background: This is the second of two papers using qualitative methods from a study of an intervention for family members affected by close relatives' substance misuse problems.

Participants: 168 primary healthcare professionals (PHCPs: GPs, practice nurses and health visitors) working in general practices in two areas of England, and who took part in the study.

Data sources: Recruitment and post-session forms completed by PHCPs; telephone interviews with each PHCP 12 weeks after recruitment of a family member; interviews with PHCPs at the end of the study.

Results: At the end of the project PHCPs were overwhelmingly positive about the family member intervention and about primary care as the appropriate site. Difficulties were encountered, however, in identifying and engaging affected family members, who were often excluded on grounds of the complexity of their problems or the level of their distress. Shortage of PHCP time and other practice-related factors added to the difficulty. Active work by a PHCP was often necessary in order to make the link between presenting symptoms of physical or mental ill-health and the existence of a family substance misuse problem. When family members were identified and recruited, PHCPs were usually positive about what was achieved. Nearly all were in favour of an approach that combined giving a self-help manual with some follow-up contact with a family member as needed.

Conclusions: Taken in conjunction with statistical outcome findings of significant reductions in symptoms and changes in ways of coping, plus qualitative analysis of the views of family members, the present results encourage the view that a flexible form of this intervention should be developed for use in primary healthcare, and that further work should build on existing strengths and attempt to overcome weaknesses identified.  相似文献   
4.
PURPOSE: Bevacizumab, a monoclonal antibody against vascular endothelial growth factor, increases survival when combined with irinotecan-based chemotherapy in first-line treatment of metastatic colorectal cancer (CRC). This randomized, phase II trial compared bevacizumab plus fluorouracil and leucovorin (FU/LV) versus placebo plus FU/LV as first-line therapy in patients considered nonoptimal candidates for first-line irinotecan. PATIENTS AND METHODS: Patients had metastatic CRC and one of the following characteristics: age > or = 65 years, Eastern Cooperative Oncology Group performance status 1 or 2, serum albumin < or = 3.5 g/dL, or prior abdominal/pelvic radiotherapy. Patients were randomly assigned to FU/LV/placebo (n = 105) or FU/LV/bevacizumab (n = 104). The primary end point was overall survival. Secondary end points were progression-free survival, response rate, response duration, and quality of life. Safety was also assessed. RESULTS: Median survival was 16.6 months for the FU/LV/bevacizumab group and 12.9 months for the FU/LV/placebo group (hazard ratio, 0.79; P = .16). Median progression-free survival was 9.2 months (FU/LV/bevacizumab) and 5.5 months (FU/LV/placebo); hazard ratio was 0.50; P = .0002. Response rates were 26.0% (FU/LV/bevacizumab) and 15.2% (FU/LV/placebo) (P = .055); duration of response was 9.2 months (FU/LV/bevacizumab) and 6.8 months (FU/LV/placebo); hazard ratio was 0.42; P = .088. Grade 3 hypertension was more common with bevacizumab treatment (16% v 3%) but was controlled with oral medication and did not cause study drug discontinuation. CONCLUSION: Addition of bevacizumab to FU/LV as first-line therapy in CRC patients who were not considered optimal candidates for first-line irinotecan treatment provided clinically significant patient benefit, including statistically significant improvement in progression-free survival.  相似文献   
5.
6.
The effect of long-term treatment of two important tobacco-specific N-nitrosamines, N'-nitrosonornicotine (NNN) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), on the depot or circulating levels of vitamin A of Swiss and BALB/c male mice was studied. It was observed that treatment of both NNN and NNK in Swiss and BALB/c mice decreased liver vitamin A levels significantly. NNK treatment also caused a decrease in the levels of vitamin A in plasma.  相似文献   
7.
Primary mesenteric venous thrombosis: a study from western India.   总被引:1,自引:0,他引:1  
INTRODUCTION: The prevalence and clinical spectrum of mesenteric venous thrombosis (MVT) in India is largely unknown. METHODS: We retrospectively re-viewed the case records of patients with primary mesenteric venous thrombosis seen over a 10-year period and retrieved information on clinical picture, underlying hypercoagulable states and outcome. RESULTS: The 28 cases (mean age 41.2 [SD 10.2] years; 19 male) included 13 with acute MVT, 10 with subacute MVT and 5 with chronic MVT. Ten patients had past thromboembolic events (multiple events in five); four patients had isolated superior mesenteric vein involvement and 14 had multiple vessel involvement. Hypercoagulable state was identified in 17 patients, with multiple etiologies in 7 patients. Pre-operative diagnosis was made in all patients. Ten patients needed surgical management; the rest were managed medically initially, but 2 required surgery on follow up. Seven patients died during a follow up of up to 10 years, with in-hospital mortality during index admission in six. CONCLUSIONS: Most of the patients with MVT have multiple intra-abdominal vessel involvement and underlying hypercoagulable state. The policy of early treatment with anticoagulation in all and surgical treatment as per need, achieves low mortality.  相似文献   
8.
9.
10.
BackgroundMesenteric internal hernia (MIH) is the most common cause of small bowel obstruction (SBO) after laparoscopic Roux-en-Y gastric bypass. Because MIH is a potentially life-threatening complication, we hypothesized that elective repair of MIH before developing acute SBO could decrease morbidity in this population.MethodsThe records of 702 consecutive patients undergoing primary laparoscopic Roux-en-Y gastric bypass from January 2002 and August 2007 were retrospectively reviewed to determine the incidence and etiology of SBO. During the last 9 months of the study, we offered elective laparoscopy to any patient who presented to us with symptoms of intermittent SBO.ResultsOf the 702 patients, 27 (3.8%) developed acute SBO. Of these 27 patients, 15 (55%) had obstruction related to an MIH. Nearly all patients had a typical history of intermittent abdominal pain, nausea, and bloating before developing acute SBO. Elective laparoscopy was offered to 11 patients with symptoms of intermittent SBO. Two patients who refused subsequently underwent operations for acute SBO. MIH was found at elective laparoscopic exploration in all cases. Of the 9 patients undergoing elective surgery, 3 (33%) had small bowel volvulus.ConclusionSBO due to MIH after laparoscopic Roux-en-Y gastric bypass is typically preceded by symptoms of intermittent obstruction. Patients who have these herald symptoms should promptly be offered elective laparoscopic exploration. Elective repair of MIH can be performed safely and expeditiously.  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