首页 | 官方网站   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   3883篇
  免费   2篇
工业技术   3885篇
  2021年   3篇
  2020年   5篇
  2019年   3篇
  2018年   2篇
  2017年   2篇
  2016年   3篇
  2014年   3篇
  2013年   8篇
  2012年   8篇
  2011年   7篇
  2010年   5篇
  2009年   6篇
  2008年   8篇
  2007年   14篇
  2006年   4篇
  2005年   15篇
  2004年   9篇
  2003年   12篇
  2002年   3篇
  2001年   8篇
  2000年   3篇
  1999年   136篇
  1998年   1259篇
  1997年   682篇
  1996年   405篇
  1995年   250篇
  1994年   198篇
  1993年   247篇
  1992年   38篇
  1991年   50篇
  1990年   49篇
  1989年   36篇
  1988年   28篇
  1987年   44篇
  1986年   25篇
  1985年   25篇
  1984年   3篇
  1983年   10篇
  1982年   15篇
  1981年   19篇
  1980年   21篇
  1979年   5篇
  1978年   9篇
  1977年   70篇
  1976年   117篇
  1975年   5篇
  1974年   2篇
  1968年   2篇
  1965年   1篇
  1955年   1篇
排序方式: 共有3885条查询结果,搜索用时 31 毫秒
951.
In a preliminary study the principles of standard gynaecological surgery, new operative laparoscopic techniques and mechanical elevation of the abdominal wall are combined. These early results indicate an advantage to both patient and hospitals from this approach. Further studies are required to verify our impressions that minilaparotomy combined with no insufflation laparoendoscopy will open up the concept of operative laparoscopic surgery to most gynaecologists.  相似文献   
952.
To observe the incidence of complications in severely hyponatraemic hospitalized patients and relate outcome to rate of correction, all patients admitted to a tertiary referral hospital in New York City, USA or a group of hospitals in Oxford, UK with a sodium < or = 120 mmol/l were studied. Review of the notes and prospective evaluation were used to ascertain cause of hyponatraemia, method of management and outcome. There were 84 episodes in New York and 100 in Oxford, over 9.5 months and one year, respectively; 79% had chronic hyponatraemia ( > 3 days duration). During hyponatraemia, 76% of patients had clouding of consciousness with 11% in coma. Other hyponatraemic complications included long track signs (including hemiparesis) (6.0%), seizures (3.3%), hallucinations (0.5%), tremor (1.0%), intellectual impairment without clouding of consciousness (0.5%), and acute psychosis (0.5%). 4.3% died as a direct result of their electrolyte disturbance. After correction, central pontine myelinolysis (0.5%), post-correction seizures (1.0%), intellectual impairment (2.2%), tremor (0.5%), paraesthesiae (0.5%), and striatal syndrome (0.5%) were observed. Correction of hyponatraemia was started in 158 patients, and the mean maximum rate of correction in 24 h was 8.4 mmol/l (SD 5.6, range 2-42). The maximum rate of correction was higher in those who developed neurological sequelae (12.1 mmol/l/24 h vs. 8.2 mmol/l/24 h; p = 0.0125, t-test, separate variance, two-tail). Neurological sequelae were associated with faster rates of correction, and correction of chronic severe hyponatraemia should be < 10 mmol/l in 24 h.  相似文献   
953.
OBJECTIVE: To assess the effect of intracervical injection of dilute (0.05 U/mL) vasopressin solution on blood loss during operative hysteroscopy. METHODS: In a randomized, double-blind study, dilute vasopressin solution or placebo (normal saline) was injected into the cervical stroma of 106 women before dilation of the cervix in preparation for operative hysteroscopy. Intraoperative bleeding was calculated by dividing the number of red blood cells per milliliter of outflow distention fluid by the number of red blood cells per milliliter of the woman's blood immediately before the procedure and multiplying this quotient by the total amount of outflow fluid collected. Pressures were kept constant with a hysteroscopic infusion pump. RESULTS: The mean (+/-standard error of the mean) intraoperative blood loss of the treated (vasopressin) and control (placebo) groups was 20.3 +/- 4.1 mL (range 0-135) and 33.4 +/- 5.4 mL (range 0-290), respectively. The volume of distention fluid intravasation in the treated and control groups was 448.5 +/- 47.0 mL (range 30-1410) and 819.1 +/- 79.7 mL (range 20-1977), respectively. The operating time in the treated and control groups was 31.1 +/- 1.2 minutes (range 18-52) and 34.1 +/- 1.3 minutes (range 19-65), respectively. For all three outcome measures, the differences between the two groups were statistically significant, but for visual clarity of the uterine cavity during surgery, the difference was not significant. CONCLUSION: Administration of dilute vasopressin solution (0.05 U/mL) to the cervical stroma significantly reduces blood loss, distention fluid intravasation, and operative time during hysteroscopy. Further evaluation is required to determine the optimum dosage.  相似文献   
954.
The impact of organizational downsizing on the job satisfaction of nurses   总被引:1,自引:0,他引:1  
Professional nurses across Canada are being affected by health reform initiatives designed to deinstitutionalize the health care system. This panel study examined the impact this restructuring has had on nurses' overall job satisfaction as well as their satisfaction with various aspects of their job and work environment. The participants consisted of 345 nurses employed in 3 community hospitals in southwestern Ontario. Hospital downsizing had relatively little effect on overall job satisfaction, satisfaction with kind of work, amount of work, and physical work conditions. However, compared to before the downsizing, nurses reported a significant deterioration in satisfaction with their career future, hospital identification, supervision, and co-workers following the implementation of restructuring initiatives. We discuss the organizational and management implications of these findings and suggest ways that hospital administrators can minimize the negative effects of downsizing on nursing professionals.  相似文献   
955.
A female infant is described with hypoglycaemia, hypotonia, obesity of the trunk and thighs, and mild dysmorphic features. Growth parameters were consistently above the 90th centile. Chromosome analysis showed her to have a derived chromosome 9 inherited from a maternal t(3;9)(p25;p23) by adjacent I segregation. She had features in common with both the dup(3p) and del(9p) syndromes. There are few reports of this chromosome rearrangement and the features are milder than expected for the degree of imbalance, complicated in males by sex reversal. The repeated reports of macrosomia may suggest an overgrowth syndrome.  相似文献   
956.
957.
Hepatitis C virus (HCV), a positive-strand RNA virus, is the major infectious agent responsible for causing chronic hepatitis. Currently, there is no vaccine for HCV infection, and the only therapy for chronic hepatitis C is largely ineffective. To investigate new genetic approaches to the management of HCV infection, six hammerhead ribozymes directed against a conserved region of the plus strand and minus strand of the HCV genome were isolated from a ribozyme library, characterized, and expressed from recombinant adenovirus vectors. The expressed ribozymes individually or in combination were efficient at reducing or eliminating the respective plus- or minus-strand HCV RNAs expressed in cultured cells and from primary human hepatocytes obtained from chronic HCV-infected patients. This study demonstrates the potential utility of ribozyme therapy as a strategy for the treatment of hepatitis C virus infection.  相似文献   
958.
The relationship between urinary symptoms and medication use was investigated in a community-based cross-sectional study involving a random sample of 2115 men 40-79 years of age in Olmsted County, Minnesota. The American Urological Association Symptom Index (AUASI) was generated from a validated self-administered questionnaire. Medication use was assessed by in-person interviews. While 1087 men reported daily medication use, only 136 reported daily use of medications known to affect urinary function adversely, including antidepressants (42), antihistamines (23), and bronchodilators (43). Age-adjusted AUASI scores were higher in men reporting daily use of antidepressants, and the association persisted after additionally adjusting for the Depression and Anxiety subscales of the General Psychological Well-Being Scale (adjusted mean difference, 2.1; 95% confidence interval (CI), 0.5-3.6; p = 0.008). The adjusted AUASI was also higher among men who took antihistamines daily (adjusted mean difference, 2.3; 95% CI, 0.3-4.3; p = 0.03). Lower age-adjusted urinary flow rates occurred with antidepressants, but not with antihistamines or bronchodilators. Clinicians evaluating men for causes of voiding dysfunction in accordance with the Agency for Health Care Policy and Research practice guideline for the diagnosis and management of benign prostatic hyperplasia should be aware that daily use of antidepressants or antihistamines may be associated with AUASI scores that are two to three points higher than in men not taking these medications.  相似文献   
959.
960.
We studied multiple determinants of graft survival at a single center and the effects of nonimmunologic graft loss on transplant survival. This retrospective study examined the results of 589 cadaver donor transplants performed between 1986 and 1992. Graft survival rates were calculated using Kaplan-Meier estimates for both overall graft survival (all causes of graft loss) and immunologic graft survival (function lost due to acute or chronic rejection and noncompliance). Cadaver graft survival was significantly poorer with an increasing degree of DR mismatch (P=0.02). An analysis of pretransplant variables showed graft loss risk was highest with greater DR mismatches, two B-antigen mismatch, higher donor serum creatinine, and younger recipient age. After transplantation, acute rejection was the most significant factor associated with long-term graft survival. Our data demonstrate a significant advantage for zero DR and one DR mismatch cadaver donor transplants, with excellent immunologic graft survival. This study suggests that a combination of immediate graft function, prevention of acute rejection by appropriate early immunosuppressive therapy, and acceptable DR match enhances cadaveric graft survival.  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-23

京公网安备 11010802026262号