全文获取类型
收费全文 | 10220篇 |
免费 | 519篇 |
国内免费 | 93篇 |
专业分类
耳鼻咽喉 | 80篇 |
儿科学 | 166篇 |
妇产科学 | 76篇 |
基础医学 | 1210篇 |
口腔科学 | 147篇 |
临床医学 | 539篇 |
内科学 | 2939篇 |
皮肤病学 | 162篇 |
神经病学 | 785篇 |
特种医学 | 420篇 |
外科学 | 1907篇 |
综合类 | 45篇 |
预防医学 | 257篇 |
眼科学 | 181篇 |
药学 | 617篇 |
中国医学 | 11篇 |
肿瘤学 | 1290篇 |
出版年
2023年 | 75篇 |
2022年 | 134篇 |
2021年 | 270篇 |
2020年 | 134篇 |
2019年 | 186篇 |
2018年 | 240篇 |
2017年 | 203篇 |
2016年 | 249篇 |
2015年 | 262篇 |
2014年 | 326篇 |
2013年 | 380篇 |
2012年 | 622篇 |
2011年 | 666篇 |
2010年 | 355篇 |
2009年 | 374篇 |
2008年 | 657篇 |
2007年 | 707篇 |
2006年 | 687篇 |
2005年 | 669篇 |
2004年 | 656篇 |
2003年 | 617篇 |
2002年 | 607篇 |
2001年 | 138篇 |
2000年 | 130篇 |
1999年 | 133篇 |
1998年 | 147篇 |
1997年 | 110篇 |
1996年 | 86篇 |
1995年 | 94篇 |
1994年 | 69篇 |
1993年 | 52篇 |
1992年 | 76篇 |
1991年 | 65篇 |
1990年 | 55篇 |
1989年 | 62篇 |
1988年 | 44篇 |
1987年 | 44篇 |
1986年 | 52篇 |
1985年 | 46篇 |
1984年 | 40篇 |
1983年 | 36篇 |
1982年 | 33篇 |
1981年 | 22篇 |
1980年 | 16篇 |
1979年 | 31篇 |
1978年 | 15篇 |
1977年 | 15篇 |
1975年 | 17篇 |
1971年 | 15篇 |
1966年 | 14篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Yasuko Tomizawa Asako Tokumine Shinji Ninomiya Naoki Momose Toru Matayoshi 《Journal of artificial organs》2008,11(3):117-122
The heart-lung machines for open-heart surgery have improved over the past 50 years; they rarely break down and are almost always equipped with backup batteries. The hand-cranking procedure only becomes necessary when a pump breaks down during perfusion or after the batteries have run out. In this study, the performance of hand cranking a roller pump was quantitatively assessed by an objective method using the ECCSIM-Lite educational simulator system. A roller pump connected to an extracorporeal circuit with an oxygenator and with gravity venous drainage was used. A flow sensor unit consisting of electromagnetic sensors was used to measure arterial and venous flow rates, and a built-in pressure sensor was used to measure the water level in the reservoir. A preliminary study of continuous cranking by a team of six people was conducted as a surprise drill. This system was then used at a perfusion seminar. At the seminar, 1-min hand-cranking drills were conducted by volunteers according to a prepared scenario. The data were calculated on site and trend graphs of individual performances were given to the participants as a handout. Preliminary studies showed that each person's performance was different. Results from 1-min drills showed that good performance was not related to the number of clinical cases experienced, years of practice, or experience in hand cranking. Hand cranking to maintain the target flow rate could be achieved without practice; however, manipulating the venous return clamp requires practice. While the necessity of performing hand cranking during perfusion due to pump failure is rare, we believe that it is beneficial for perfusionists and patients to include hand-cranking practice in periodic extracorporeal circulation crisis management drills because a drill allows perfusionists to mentally rehearse the procedures should such a crisis occur. 相似文献
102.
103.
104.
The immunohistochemical localization of three triplet proteins of neurofilaments in normal Kultschitsky cells and tumourlets of the human lung has been studied using avidin-biotin-peroxidase complex (ABC) method. Kultschitsky cells and tumourlets have been stained with antisera against 68 K, 150 K and 200 K dalton components of the neurofilaments, respectively. Ultrastructural observations of human Kultschitsky cells have revealed the presence of bundles of intermediate filaments as well as microtubules and neurosecretory-type granules. In the tumourlets, similarly sized filaments were found, but were relatively scarce. Since intermediate filaments are thought to be specific to differentiated cells and neurofilament proteins are restricted to the neuronal tissues, we conclude that Kultschitsky cells of the lung are of neuronal nature. 相似文献
105.
M Aiba H Iri H Suzuki K Kageyama T Kawai O Abe M Murai H Tazaki T Saruta 《Archives of pathology & laboratory medicine》1985,109(4):357-360
Pathologic study of a rare 11-deoxycorticosterone-producing adrenocortical tumor causing primary aldosteronismlike signs and symptoms, revealed several characteristic features as follows: (1) fairly large size with histologic features corresponding to those of benign zone glomerulosa-type aldosteronoma, (2) lack of spironolactone (S) bodies despite S administration, and (3) heavy mast cell infiltration. In order to explain this rare histology, the localization of mast cells in the adrenal glands and functioning adrenocortical tumors of 67 surgical specimens were investigated. The results of the study supported the view that detection of mast cells helps in the differentiation of mineralocorticoid-producing tumors from cortisol-producing ones, and that the observed mast cell infiltration was due, in part, to its production of 11-deoxycorticosterone. 相似文献
106.
Ogawa Y Kobayashi T Nishioka A Kariya S Hamasato S Seguchi H Yoshida S 《International journal of molecular medicine》2003,11(2):149-152
Previously, we demonstrated that human peripheral T lymphocytes revealed early apoptotic changes (annexin V-positive) and late apoptotic changes (propidium iodide-positive), at 13 and 24 h, respectively, after irradiation of 5 Gy. Changes in mitochondrial membrane potential were observed at 10 h after irradiation of 5 Gy. Subsequently, mitochondrial cytochrome c-release was confirmed. In order to elucidate the mechanism which acts prior to the mitochondrial membrane potential changes, we examined in the previous study the radiation dose and the timing of oxidative DNA damage induced in human peripheral T lymphocytes following 10 MV X-ray irradiation. As a result, the production of 8-oxoguanine, i.e., the product of oxidative DNA damage, was clearly identified starting at 10, 6, and 3 h, after 2, 5, and 20 Gy of irradiation, respectively. Therefore, we examined in the present study reactive oxygen species (ROS) formation in T lymphocytes following 5 Gy of irradiation. Using a CCD camera system, we monitored fluorescence in T lymphocytes loaded with the succinimidyl ester of dichlorodihydrofluorescein diacetate (H2DCFDA), which is non-fluorescent until oxidized by ROS. We found that ROS formation occurred immediately after irradiation, continued for several hours, and resulted in oxidative DNA damage. Therefore, the origin of hyper-radiosensitivity of T lymphocytes seemed to be the high production of ROS in the mitochondrial DNA following irradiation. 相似文献
107.
108.
109.
Summary Seventy-one Caucasian orbits (36 right, 35 left) were studied by dissection. The diameter of the ophthalmic a. (2 mm from the origin) was 1.54 ± 0.04 mm (male) and 1.31 ± 0.05 mm (female). In individual cases, there were no significant differences in vessel diameter between the right and left sides but, differences in vessel diameter between males and females were more commonly observed in the arteries which leave the orbit (extraorbital group), the individual vessels having a larger diameter in males. The incidence of the ophthalmic a. passing in the orbit medially under the optic n. was 18.6%. The lacrimal a. was observed to arise from the ophthalmic a. in only 82.5% of the cases examined, 15.9% of the cases showed the origin to be at the anastomotic branch of the middle meningealThis article is dedicated to Pr Dr Hoepke on occasion of his 100th birthday 相似文献
110.
Extranodal formation of lymphoid follicles was morphologically studied in experimental bronchopneumonia. Control gnotobiotic mice had no peribronchial lymphoid follicles and only lymphatic vessels were traced from the terminal bronchiolar region toward larger bronchi. During the week after intranasal inoculation of mycoplasma pulmonis, lymphoid follicles developed in the terminal portion of the lymphatics by the accumulation of small lymphocytes. A loose network of mesenchymal cells and early infiltration of macrophages, following stromal edema, seemed to play an important role in the early accumulation of lymphocytes. Blastic transformation was seen frequently in the center of the accumulated lymphocytes. Two weeks after inoculation plasma cells emerged conspicuously in the periphery of the lymphoid follicles, and the acute phase of bronchopneumonia began to subside. Typical germinal centers with tingible body macrophages and dendritic reticulum cells developed when the bronchitis persisted in a chronical manner. 相似文献