全文获取类型
收费全文 | 9548篇 |
免费 | 667篇 |
国内免费 | 283篇 |
专业分类
耳鼻咽喉 | 92篇 |
儿科学 | 176篇 |
妇产科学 | 129篇 |
基础医学 | 835篇 |
口腔科学 | 554篇 |
临床医学 | 910篇 |
内科学 | 1506篇 |
皮肤病学 | 174篇 |
神经病学 | 1265篇 |
特种医学 | 699篇 |
外国民族医学 | 4篇 |
外科学 | 1067篇 |
综合类 | 1397篇 |
现状与发展 | 1篇 |
预防医学 | 334篇 |
眼科学 | 123篇 |
药学 | 428篇 |
5篇 | |
中国医学 | 215篇 |
肿瘤学 | 584篇 |
出版年
2024年 | 20篇 |
2023年 | 164篇 |
2022年 | 290篇 |
2021年 | 417篇 |
2020年 | 360篇 |
2019年 | 319篇 |
2018年 | 292篇 |
2017年 | 317篇 |
2016年 | 308篇 |
2015年 | 310篇 |
2014年 | 558篇 |
2013年 | 507篇 |
2012年 | 469篇 |
2011年 | 467篇 |
2010年 | 413篇 |
2009年 | 460篇 |
2008年 | 485篇 |
2007年 | 529篇 |
2006年 | 450篇 |
2005年 | 380篇 |
2004年 | 304篇 |
2003年 | 268篇 |
2002年 | 276篇 |
2001年 | 235篇 |
2000年 | 183篇 |
1999年 | 156篇 |
1998年 | 132篇 |
1997年 | 161篇 |
1996年 | 131篇 |
1995年 | 115篇 |
1994年 | 117篇 |
1993年 | 90篇 |
1992年 | 93篇 |
1991年 | 65篇 |
1990年 | 65篇 |
1989年 | 54篇 |
1988年 | 55篇 |
1987年 | 50篇 |
1986年 | 65篇 |
1985年 | 89篇 |
1984年 | 51篇 |
1983年 | 31篇 |
1982年 | 37篇 |
1981年 | 40篇 |
1980年 | 31篇 |
1979年 | 14篇 |
1978年 | 14篇 |
1976年 | 13篇 |
1975年 | 14篇 |
1973年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
应用显微分光光度计测定15例鼻咽癌19处癌旁病变的上皮细胞核DNA含量并与浸润癌相比较。中、重度异型增生上皮细胞核DI及超过2.5c细胞的百分数处于单纯增生+轻度异型增生与浸润癌之间,3组DI及超过2.5c细胞的百分数差异显著。中、重度异型增生以非整倍体为主,其细胞核DNA含量组方图相似于浸润癌。从细胞核DNA含量角度来看,中、重度异型增生是重要的癌前病变。 相似文献
22.
M Vergnes 《Physiology & behavior》1975,14(3):271-276
Long-Evans hooded rats were tested for emotionality and observed by pairs in an open field for 6 consecutive days. Postoperative observations indicated that both emotionality and social cohesiveness were dramatically altered by ventromedial and anterolateral hypothalamic lesions. Tegmental, interpeduncular and habenular lesions were shown to have no effect on these behaviors. Alterations in behavior observed following hypothalamic ablations were related to septal and amygdaloid effects, and the possibility of separate projection systems for emotionality and social cohesiveness was discussed. 相似文献
23.
Enhanced responsiveness of human extravisual areas to photic stimulation in patients with severely reduced vision 总被引:1,自引:0,他引:1
Rausch M Widdig W Eysel UT Penner IK Tegenthoff M 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》2000,135(1):34-40
Lesions in the primary visual cortex induce severe loss of visual perception. Depending on the size of the lesion, the visual field might be affected by small scotomas, hemianopia, or complete loss of vision (cortical blindness). In many cases, the whole visual field of the patient is affected by the lesion, but diffuse light-dark discrimination remains (residual rudimentary vision, RRV). In other cases, a sparing of a few degrees can be found (severely reduced vision, SRV).In a follow-up study, we mapped visually induced cerebral activation of three subjects with SRV using functional magnetic resonance imaging. We were especially interested in the visual areas that would be activated if subjects could perceive the stimulus consciously although information flow from V1 to higher visual areas was strongly reduced or virtually absent. Because subjects were only able to discriminate strong light from darkness, we used goggles flashing intense red light at a frequency of 3 Hz for full visual field stimulation. Besides reduced activation in V1, we found activation in the parietal cortex, the frontal eye fields (FEF), and the supplementary eye fields (SEF). In all patients, FEF activation was pronounced in the right hemisphere. These patterns were never seen in healthy volunteers. In a patient who recovered completely, we observed that extrastriate activation disappeared in parallel with the visual field restitution. This result suggests that damage to the primary visual cortex changes the responsiveness of parietal and extravisual frontal areas in patients with SRV. This unexpected result might be explained by increased stimulus-related activation of attention-related networks. 相似文献
24.
F. Rothe G. Wolf 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1994,79(2):400-404
Summary The behaviour of enzymes putatively involved in glutamate/aspartate transmitter metabolism (glutamate dehydrogenase, aspartate aminotransferase, alanine aminotransferase,-glutamyltranspeptidase) was studied in the striatum 3, 7, 14 days and 7 weeks after mechanical destruction of corticostriatal fibres. For a period of up to seven days after unilateral lesion, enzyme activities were significantly diminished (by up to 13% based on protein) in the ipsilateral striatum as compared to the striatum of the intact side. Later, the enzyme activities in the ipsilateral striatum recovered. After seven weeks, an increase was observed for glutamate dehydrogenase activity, whereas the activity of alanine aminotransferase showed a transient rise at the end of the second week. The decrease in enzyme levels is interpreted as being attributable to the destruction of nerve endings which are considered to be glutamatergic, interfering with various compensating processes (e.g. glial cell proliferation) which occur with advancing times after lesion. 相似文献
25.
Rats having either sham operations or one-stage bilateral lesions of the two somatosensory areas of the cortex were tested for acquisition of five tactile discriminations after postoperative recovery intervals of 14, 35, 180, 365 or 730 days. The group with lesions performed worse than its time-matched control group in every instance, and there was no evidence for recovery of function with the longer postoperative recovery periods. These results suggest that time per se is not a significant determinant of restitution after somatosensory cortical ablations. 相似文献
26.
M. B. Bromberg G. Pamel B. S. Stephenson A. B. Young J. B. Penney 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1987,69(1):53-59
Summary High affinity glutamate uptake into corticofugal fiber terminals was measured in the ventrolateral thalamus and red nucleus at varying time intervals after lesions were made by kainic acid in the contralateral interpositus nucleus of the cerebellum in rats. Under similar conditions the density of cortical fiber terminals was estimated using the Fink-Heimer impregnation technique. 1. Glutamate uptake steadily increased in the ventrolateral thalamus up to 60 days after lesions in the contralateral cerebellum. 2. Similar changes were noted in the red nucleus. 3. The changes were dependent on the integrity of corticofugal fibers to the thalamus and red nucleus. 4. No changes in uptake of gammaaminobutyric acid were noted. 5. Saturation curves for glutamate uptake suggested a change in the maximal number of transport sites. 6. Fink-Heimer degeneration studies showed an increase in cortical terminals in the ipsilateral ventrolateral thalamus and in both rostral and caudal regions of the red nucleus following lesions in the contralateral interpositus nucleus. The data are consistent with an increase in the number of cortical fiber terminals in reaction to loss of cerebellar input to the ventrolateral thalamus and red nucleus. This study correlates anatomical and biochemical evidence for collateral sprouting in a model based on electrophysiologic data in the red nucleus and extends the model to include the thalamus. 相似文献
27.
B Srebro 《Physiology & behavior》1973,11(1):103-105
Eight successive position reversals were given preoperatively to establish position reversal sets in rats. Six animals received septal lesions, six fronto-polar cortex ablations, and six normals served as a control group. During a series of eight postoperative reversals, rats with septal lesions committed significantly more errors and approach errors than normals while fronto-polar ablations had no detectable effect. 相似文献
28.
目的:通过对食管和贲门癌原发病灶和淋巴结转移病灶肿瘤抑制基因p53变化规律的研究,加深对食管和贲门癌转移发生的分子学基础的了解。方法:采用组织病理学和免疫组织化学(ABC)方法,对31例手术切除的食管和贲门癌原发病灶和转移病灶肿瘤抑制基因p53蛋白聚集进行比较研究。结果:31例手术标本中,病理检查发现24例食管鳞状细胞癌,7例为贲门腺癌。研究表明:24例食管原发和转移鳞癌中,11例原发和转移病灶中均出现p53蛋白聚集的变化,原发和转移病灶的一致性变化发生率为61%(11/18);在6例原发病灶p53免疫组化阴性患者中,其淋巴结转移病灶也同时出现免疫阴性反应。在7例胃贲门腺癌中,3例原发和转移病灶同时出现p53免疫阳性表达的一致率为50%(3/6);1例原发病灶p53免疫组化阴性患者,其淋巴结转移病灶也出现阴性反应。结论:肿瘤抑制基因p53在食管和贲门癌癌变和转移中起一定的作用。可能是食管和贲门癌侵袭与转移过程中值得重视的生物学指标之一。 相似文献
29.
J. -L. Vercher G. M. Gauthier 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1988,73(1):155-166
Summary When the hand of the observer is used as a visual target, oculomotor performance evaluated in terms of tracking accuracy, delay and maximal ocular velocity is higher than when the subject tracks a visual target presented on a screen. The coordination control exerted by the motor system of the arm on the oculomotor system has two sources: the transfer of kinaesthetic information originating in the arm which increases the mutual coupling between the arm and the eyes and information from the arm movement efferent copy which synchronizes the motor activities of both subsystems (Gauthier et al. 1988; Gauthier and Mussa-Ivaldi 1988). We investigated the involvement of the cerebellum in coordination control during a visuo-oculo-manual tracking task. Experiments were conducted on baboons trained to track visual targets with the eyes and/or the hand. The role of the cerebellum was determined by comparing tracking performance defined in terms of delay, accuracy (position or velocity tracking errors) and maximal velocity, before and after lesioning the cerebellar dentate nucleus. Results showed that in the intact animal, ocular tracking was more saccadic when the monkey followed an external target than when it moved the target with its hand. After lesioning, eye-alone tracking of a visual target as well as eye-and-hand-tracking with the hand contralateral to the lesion was little if at all affected. Conversely, ocular tracking of the hand ipsilateral to the lesion side became more saccadic and the correlation between eye and hand movement decreased considerably while the delay between target and eyes increased. In normal animals, the delay between the eyes and the hand was close to zero, and maximal smooth pursuit velocity was around 100 degrees per second with close to unity gain; in eye-alone tracking the delay and maximal smooth pursuit velocity were 200 ms and 50 deg per second, respectively. After lesioning, delay and maximum velocity were respecttively around 210 ms and 40 deg per second, that is close to the values measured in eye-alone tracking. Thus, after dentate lesioning, the oculomotor system was unable to use information from the motor system of the arm to enhance its performance. We conclude that the cerebellum is involved in the coordination control between the oculomotor and manual motor systems in visuo-oculo-manual tracking tasks. 相似文献
30.
Changes at the glomerular tip: a feature of membranous nephropathy and other disorders associated with proteinuria 总被引:1,自引:0,他引:1
A J Howie 《The Journal of pathology》1986,150(1):13-20
Renal biopsies and post-mortem kidneys were examined for segmental lesions at glomerular tips, consisting of adhesion of the tuft to Bowman's capsule with an area of intra-capillary foam cells or hyaline material or sclerosed material. Of 72 consecutive renal biopsies showing membranous nephropathy, 46 (64 per cent) had tip changes. Such changes were correlated with the presence of acute tubular damage and with later stages of the nephropathy, but otherwise seemed unrelated to any particular clinical or pathological feature. Fourteen other patients were identified whose renal biopsies showed tip changes in glomeruli that had segmental or global mesangial hypercellularity not of a well-recognized type such as IgA nephropathy. These patients had persistent proteinuria unresponsive to steroids. Tip changes were also seen in several miscellaneous conditions including IgA nephropathy and diabetic glomerulosclerosis. These findings demonstrate that tip changes are seen in many disorders of the kidney associated with proteinuria and represent a previously unrecognized common response of the glomerulus to some insult, the glomerular tip lesion, as originally defined, is distinguished by the apparent normality of tufts except for the tip changes and can be regarded as presumed minimal change nephropathy plus tip changes and when tip changes are seen, the most important factor determining the prognosis is the condition of the rest of the glomerular tuft. 相似文献