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   31604篇
  免费   1618篇
  国内免费   76篇
耳鼻咽喉   552篇
儿科学   745篇
妇产科学   502篇
基础医学   4701篇
口腔科学   951篇
临床医学   2789篇
内科学   5637篇
皮肤病学   722篇
神经病学   3368篇
特种医学   2001篇
外国民族医学   1篇
外科学   4485篇
综合类   254篇
一般理论   6篇
预防医学   2235篇
眼科学   847篇
药学   1818篇
中国医学   33篇
肿瘤学   1651篇
  2021年   364篇
  2020年   229篇
  2019年   337篇
  2018年   473篇
  2017年   372篇
  2016年   505篇
  2015年   565篇
  2014年   732篇
  2013年   931篇
  2012年   1530篇
  2011年   1494篇
  2010年   971篇
  2009年   910篇
  2008年   1406篇
  2007年   1587篇
  2006年   1568篇
  2005年   1581篇
  2004年   1448篇
  2003年   1325篇
  2002年   1381篇
  2001年   962篇
  2000年   857篇
  1999年   750篇
  1998年   397篇
  1997年   306篇
  1996年   269篇
  1995年   282篇
  1994年   236篇
  1993年   211篇
  1992年   468篇
  1991年   511篇
  1990年   455篇
  1989年   438篇
  1988年   421篇
  1987年   346篇
  1986年   358篇
  1985年   377篇
  1984年   317篇
  1983年   265篇
  1982年   194篇
  1981年   206篇
  1980年   183篇
  1979年   348篇
  1978年   235篇
  1977年   235篇
  1976年   184篇
  1975年   224篇
  1974年   208篇
  1973年   206篇
  1972年   223篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
A statistical method for determining suitability for community placement   总被引:1,自引:0,他引:1  
The authors developed a statistically based method for determining whether inpatient or outpatient placement is most appropriate for a given patient. This study assesses the method's accuracy by comparing statistical classifications of a random sample of inpatients at five New York State facilities with the classifications of multidisciplinary clinical teams. The statistical method proved to be very strong in screening patients who should not be considered for community placement and in four of the five facilities was also strong in identifying appropriate outpatients. The authors discuss the method's implications for outpatient screening and outpatient programs.  相似文献   
92.
Selective laser trabeculoplasty in phakic and pseudophakic eyes.   总被引:2,自引:0,他引:2  
BACKGROUND AND OBJECTIVE: To evaluate the effect of pseudophakia on the success of selective laser trabeculoplasty in lowering intraocular pressure (IOP). PATIENTS AND METHODS: In this retrospective, nonrandomized clinical trial, a chart review of all patients who underwent selective laser trabeculoplasty from September 2002 to June 2004 using a frequency-doubled Q-switched 532-nm Nd:YAG laser was performed. Changes in IOP and statistical significance were determined at each follow-up period. Average decrease in IOP and success rates for phakic and pseudophakic eyes were compared statistically at each time period. RESULTS: In the phakic group, mean IOP decreased from 18.1 to 15.5 mm Hg (P < .0005) and mean glaucoma medication use decreased from 2.1 to 1.6 medications after 24 months of follow-up. In the pseudophakic group, mean IOP decreased from 18.3 to 15.2 mm Hg (P < .005) and mean glaucoma medication use decreased from 2.2 to 1.6 medications. Success rates ranged from 54% to 67% in the phakic group and 52% to 65% in the pseudophakic group. No statistically significant difference between phakic and pseudophakic eyes in decreased IOP or success rates was seen at any time point (P > .05). No significant complications occurred in either group. CONCLUSIONS: Selective laser trabeculoplasty is effective in lowering IOP in both phakic and pseudophakic patients.  相似文献   
93.
94.
Spectral sensitivity was measured for nine infants, 4-6 weeks of age, and three adults under conditions of chromatic adaptation chosen to reveal the presence of short-wavelength-sensitive cones. Monochromatic test stimuli (400-550 nm) were presented at 2 Hz superimposed on a broadband, yellow background. Following 4 min of adaptation to the background, test stimuli were presented while recording the steady-state, visually-evoked cortical potential (VECP). Response averages were obtained for several radiance levels at each test wavelength, and the amplitude of the fundamental frequency was extracted from the digitized response with a fast-Fourier transform. These data were used to construct response vs intensity functions for each wavelength. A fixed criterion response was chosen from the latter family of functions to generate individual spectral sensitivity curves. These VECP spectral sensitivity functions matched the psychophysically-determined functions of adults, measured by the method of adjustment and with the same stimulus configuration. Peak sensitivity for infants and adults under these conditions occurred at about 440 nm, and the main lobe of the curve (400-500 nm) was well fitted by the Vos-Walraven short-wavelength cone fundamental. The only major difference between the infant and adult data was in the relative sensitivity of the secondary mode of the curves (above 500 nm). These results demonstrate the presence of short-wavelength-sensitive cones and a functional pathway to the visual cortex by 4-6 weeks of age.  相似文献   
95.
Although the partial benzodiazepine receptor inverse agonist, Ro 15-4513, counteracts many ethanol effects, its effect on operant behavior or on ethanol-induced changes in this behavior, remains controversial. In this study, we examined the effects of Ro 15-4513, ethanol, and their interaction on behavior maintained by an FR 20 schedule of food reinforcement. Ro 15-4513 (1.0-4.0 mg/kg) and ethanol (1.5-3.0 g/kg) reduced lever-responding of both male and female mice. The disruptive effect of Ro 15-4513 was of short duration (approximately 10 min), and was greater in male than in female mice. Under equivalent dose and time parameters, ethanol disrupted behavior of both sexes to the same extent. In spite of the disruptive effects of both drugs when given alone, when given after ethanol and prior to testing, Ro 15-4513 attenuated the disruptive effects of ethanol in male mice. The present study extends previous reports by documenting: (1) that the disruptive effect of Ro 15-4513 on mice is of very short duration and occurs at lower doses than previously reported; (2) that, in spite of being disruptive itself, Ro 15-4513 can attenuate the disruptive effects of ethanol on schedule controlled behavior; and (3) that gender is an important consideration in determining the effects of this compound.  相似文献   
96.
97.
Neuropathological findings in two siblings with familial erythrophagocytic lymphohistiocytosis (FEL) are reported. Case 1 showed the typical neuropathological findings of FEL with lymphohistiocytic infiltration of the leptomeninges and perivascular spaces. A characteristic erythrophagocytosis was detected in inguinal lymph nodes, lung and bone marrow. Case 2 revealed calcification and necrotic lesions in the brain. In the necrotic areas, parenchymal calcification, vascular medial calcification, and occlusion of many vessels due to subendothelial fibrosis were detected. The areas of necrosis correlated with the distribution of occluded vessels. These changes were most prominent in putamen, internal capsule, thalamus and dentate nucleus. Hypercytokinemia is suspected to be the underlying mechanism for the clinical and laboratory findings in patients with FEL, although the relationship to the vascular pathology is unclear.  相似文献   
98.
A proprioceptive deficit is an important determinant of disability in various shoulder disorders, such as instability and osteoarthrosis. In 15 patients with impingement syndrome stage II (Neer 1983), who were treated by arthroscopic subacromial decompression, we measured movement sense by determining threshold levels for the perception of motion of the shoulder. The patients were placed in a specially designed chair allowing continuous passive motion of the shoulder joint, while avoiding cutaneous, auditory and visual stimuli. To assess movement detection thresholds, passive abduction movements of the shoulder were performed at a starting angle of 60°, an amplitude of 10° and an angular velocity of 1.3°/s. Before surgery, all patients had higher threshold levels for the perception of motion in their affected shoulders then in the other side. After decompression, proprioception had improved on the decompressed side, but was unchanged on the other side.  相似文献   
99.
Utilizing a lateral fluid percussion injury as a model of cerebral concussion, rats were studied histochemically measuring the degree of cytochrome oxidase activity present within different structures at different times following injury. After concussion, the cerebral cortex ipsilateral to the site of injury exhibited a diffuse decrease in its level of chromotome oxidase (CO) activity beginning at as soon as one day and lasting for up to 10 days after the insult. The ipsilateral dorsal hippocampus also exhibited an injury-induced decrease in CO activity, however, it was not as severe as in the cortex. These results indicate that oxidative metabolism is depressed primarily within the cerebral cortex and hippocampus for several days following a cerebral concussion. We propose that this period of metabolic depression may delineate a period of time during which the injured brain is unable to function normally and thus would be vulnerable to a second insult.  相似文献   
100.
The diagnosis of idiopathic Parkinson's disease (PD) can be achieved with high degrees of accuracy in cases with full expression of classical clinical features. However, diagnostic uncertainty remains in early disease with subtle or ambiguous signs. Functional imaging has been suggested to increase the diagnostic yield in parkinsonian syndromes with uncertain clinical classification. Loss of striatal dopamine nerve terminal function, a hallmark of neurodegenerative Parkinsonism, is strongly related to decreases of dopamine transporter (DAT) density, which can be measured by single photon emission computed tomography (SPECT). The use of DAT‐SPECT facilitates the differential diagnosis in patients with isolated tremor symptoms not fulfilling PD or essential tremor criteria, drug‐induced, psychogenic and vascular Parkinsonism as well as dementia when associated with Parkinsonism. This review addresses the value of DAT‐SPECT in early differential diagnosis, and its potential as a screening tool for subjects at risk of developing PD as well as issues around the assessment of disease progression. © 2007 Movement Disorder Society  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