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   8625篇
  免费   608篇
  国内免费   106篇
耳鼻咽喉   64篇
儿科学   228篇
妇产科学   402篇
基础医学   970篇
口腔科学   204篇
临床医学   1048篇
内科学   1710篇
皮肤病学   88篇
神经病学   717篇
特种医学   344篇
外科学   1111篇
综合类   240篇
一般理论   4篇
预防医学   472篇
眼科学   194篇
药学   717篇
中国医学   84篇
肿瘤学   742篇
  2023年   35篇
  2022年   75篇
  2021年   182篇
  2020年   105篇
  2019年   179篇
  2018年   217篇
  2017年   178篇
  2016年   182篇
  2015年   246篇
  2014年   298篇
  2013年   393篇
  2012年   547篇
  2011年   626篇
  2010年   437篇
  2009年   367篇
  2008年   504篇
  2007年   514篇
  2006年   525篇
  2005年   461篇
  2004年   399篇
  2003年   332篇
  2002年   296篇
  2001年   274篇
  2000年   229篇
  1999年   199篇
  1998年   104篇
  1997年   90篇
  1996年   82篇
  1995年   60篇
  1994年   49篇
  1993年   48篇
  1992年   113篇
  1991年   120篇
  1990年   99篇
  1989年   82篇
  1988年   77篇
  1987年   78篇
  1986年   47篇
  1985年   46篇
  1984年   35篇
  1983年   36篇
  1982年   23篇
  1981年   26篇
  1980年   27篇
  1979年   28篇
  1978年   38篇
  1977年   21篇
  1975年   19篇
  1974年   26篇
  1968年   18篇
排序方式: 共有9339条查询结果,搜索用时 15 毫秒
1.
Rhabdomyolysis is a syndrome of skeletal muscle injury with release of cellular constituents such as potassium,phosphate,urate and intracellular proteins such as myoglobin into the circulation,which may cause complications including acute kidney injury,electrolyte disturbance and cardiac instability.Abnormal liver function tests are frequently observed in cases of severe rhabdomyolysis.Typically,there is an increase in serum aminotransferases,namely aspartate aminotransferase and alanine aminotransferase.This raises the question of liver injury and often triggers a pathway of investigation which may lead to a liver biopsy.However,muscle can also be a source of the increased aminotransferase activity.This review discusses the dilemma of finding abnormal liver function tests in the setting of muscle injury and the potential implications of such an association.It delves into some of the clinical and experimental evidence for correlating muscle injury to raised aminotransferases,and discusses pathophysiological mechanisms such as oxidative stress which may cause actual liver injury.Serum aminotransferases lack tissue specificity to allow clinicians to distinguish primary liver injury from muscle injury.This review also explores potential approaches to improve the accuracy of our diagnostic tools,so that excessive or unnecessary liver investigations can be avoided.  相似文献   
2.
3.
Introduction: Malnutrition increases the risk of cancer treatment-related complications. Nutritional intervention is beneficial for the outcomes of outpatients with cancer. This study investigated the impacts of nutrition consultation and care on energy intake and weight change in inpatients receiving cancer treatment.

Methods: We conducted a longitudinal study, enrolling 3221 inpatients with head and neck, lung, hepatobiliary, upper gastrointestinal, colorectal, breast, or gynecological cancer who received at least two nutrition consultations between April 2010 and July 2015. In every consultation, a dietitian calculated the total energy requirement and the actual energy intake was assessed using a 24-h dietary recall.

Results: Patients with head and neck cancer lost the most weight (1.16?kg/mo). For every consultation, a 0.03-kg weight gain per month was observed (P?=?0.001). The average energy consumption percentage (% estimated energy requirement) at the third consultation was 87.0%. After controlling for potential covariates, the energy consumption percentages at the third, fourth, fifth–seventh, eighth, and subsequent consultations were significantly higher than those at the first consultation (P?<?0.05).

Conclusion: For oncology inpatients, routine screening and at least three active nutrition consultations with dietitians effectively improved energy intake and preserved body weight.  相似文献   

4.

Context

Family caregivers constitute a critical component of the end-of-life care system with considerable cost to themselves. However, the joint association of terminally ill cancer patients' symptom distress and functional impairment with caregivers' subjective caregiving burden, quality of life (QOL), and depressive symptoms remains unknown.

Objectives/Methods

We used multivariate hierarchical linear modeling to simultaneously evaluate associations between five distinct patterns of conjoint symptom distress and functional impairment (symptom-functional states) and subjective caregiving burden, QOL, and depressive symptoms in a convenience sample of 215 family caregiver–patient dyads. Data were collected every 2 to 4 weeks over patients' last 6 months.

Results

Caregivers of patients in the worst symptom-functional states (States 3–5) reported worse subjective caregiving burden and depressive symptoms than those in the best two states, but the three outcomes did not differ between caregivers of patients in State 3 and States 4–5. Caregivers of patients in State 5 endured worse subjective caregiving burden and QOL than those in State 4. Caregivers of patients in State 4 suffered worse subjective caregiving burden and depressive symptoms but comparable QOL to those in State 2.

Conclusion

Patients' five distinct, conjoint symptom-functional states were significantly and differentially associated with their caregivers' worse subjective caregiving burden, QOL, and depressive symptoms while caring for patients over their last 6 months.  相似文献   
5.
6.
PURPOSE: The aim of this study was to investigate the effects of bimatoprost 0.03% on ocular hemodynamics in patients with normal tension glaucoma (NTG). METHODS: Twenty-two (22) patients with NTG were consecutively recruited. After basic eye examination and diurnal intraocular pressure (IOP) measurement, color Doppler imaging was used to measure the peak systolic and end diastolic velocities and resistive index of the central retinal, lateral posterior ciliary, and medial posterior ciliary arteries. Patients received bimatoprost 0.03% for 4 weeks, and these measurements were then repeated. The worse eye of each NTG patient was used in the statistical analysis. RESULTS: Bimatoprost 0.03% significantly reduced mean IOP from 15.1 +/- 3.8 mmHg at baseline to 12.0 +/- 2.9 mmHg after treatment in our sample of NTG patients (P < 0.001). No significant changes in blood velocities or resistance indices were observed in the retrobulbar vessels after the 4-week treatment. CONCLUSIONS: Topical bimatoprost 0.03% significantly reduced IOP in our NTG patients without causing significant hemodynamic changes in the retrobulbar vessels.  相似文献   
7.
This paper considers a dynamic pricing problem over a finite horizon where demand for a product is a time‐varying linear function of price. It is assumed that at the start of the horizon there is a fixed amount of the product available. The decision problem is to determine the optimal price at each time period in order to maximize the total revenue generated from the sale of the product. In order to obtain structural results we formulate the decision problem as an optimal control problem and solve it using Pontryagin's principle. For those problems which are not easily solvable when formulated as an optimal control problem, we present a simple convergent algorithm based on Pontryagin's principle that involves solving a sequence of very small quadratic programming (QP) problems. We also consider the case where the initial inventory of the product is a decision variable. We then analyse the two‐product version of the problem where the linear demand functions are defined in the sense of Bertrand and we again solve the problem using Pontryagin's principle. A special case of the optimal control problem is solved by transforming it into a linear complementarity problem. For the two‐product problem we again present a simple algorithm that involves solving a sequence of small QP problems and also consider the case where the initial inventory levels are decision variables. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   
8.
Kim  SH; Chang  KH; Song  IC; Han  MH; Kim  HC; Kang  HS; Han  MC 《Radiology》1997,204(1):239
  相似文献   
9.
Stroke is a debilitating disease that affects millions each year.While in many cases cerebral ischemic in jury can be limited by effectivw resuscitation or thrombolytic treatment,the injured neurons wither in a process known as delayed neuronal death(DND).Mounting evidence indicates that DND is not simply necrosis played out in slow motion but apoptosis is triggered.Of particular interest are two groups of signal proteins that participate in apoptosis-cyclin dependent kinases(CDKs) and p53-among a myriad of signaling events after an ischemic insult.Recent investigations have shown that CDKs,a family of enzymes initially known for their role in cell cycle regulation,are activated in injured neurons in DND.As for p53,new reports suggest that its up-regulation may represent a failed attempt to rescue in jured neurons,although its up-regulation was previously considered an indication of apoptosis.These observations thus rekindle an old quest to identify new neuroprotective targets to minimize the stroke damage.In this review,the author will examine the evidence that indicates the participation of CDKs and p53 in DND and then introduce pre-clinical data to explore CDK inhibition as a potential neuroprotective target.Finally,using CDK inhibition as an example,this paper will discuss the pertinent criteria for a viable neuroprotective strategy for ischemic in jury.  相似文献   
10.
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