全文获取类型
收费全文 | 13593篇 |
免费 | 633篇 |
国内免费 | 96篇 |
专业分类
耳鼻咽喉 | 108篇 |
儿科学 | 280篇 |
妇产科学 | 118篇 |
基础医学 | 1546篇 |
口腔科学 | 206篇 |
临床医学 | 758篇 |
内科学 | 3758篇 |
皮肤病学 | 285篇 |
神经病学 | 927篇 |
特种医学 | 430篇 |
外科学 | 2868篇 |
综合类 | 90篇 |
预防医学 | 321篇 |
眼科学 | 201篇 |
药学 | 782篇 |
中国医学 | 33篇 |
肿瘤学 | 1611篇 |
出版年
2023年 | 104篇 |
2022年 | 209篇 |
2021年 | 352篇 |
2020年 | 154篇 |
2019年 | 240篇 |
2018年 | 277篇 |
2017年 | 249篇 |
2016年 | 310篇 |
2015年 | 326篇 |
2014年 | 449篇 |
2013年 | 514篇 |
2012年 | 920篇 |
2011年 | 942篇 |
2010年 | 491篇 |
2009年 | 466篇 |
2008年 | 793篇 |
2007年 | 819篇 |
2006年 | 863篇 |
2005年 | 818篇 |
2004年 | 829篇 |
2003年 | 818篇 |
2002年 | 814篇 |
2001年 | 226篇 |
2000年 | 172篇 |
1999年 | 244篇 |
1998年 | 188篇 |
1997年 | 136篇 |
1996年 | 122篇 |
1995年 | 118篇 |
1994年 | 93篇 |
1993年 | 109篇 |
1992年 | 97篇 |
1991年 | 121篇 |
1990年 | 107篇 |
1989年 | 118篇 |
1988年 | 87篇 |
1987年 | 88篇 |
1986年 | 85篇 |
1985年 | 73篇 |
1984年 | 42篇 |
1983年 | 43篇 |
1982年 | 31篇 |
1981年 | 20篇 |
1980年 | 27篇 |
1979年 | 33篇 |
1978年 | 28篇 |
1977年 | 25篇 |
1975年 | 14篇 |
1974年 | 16篇 |
1972年 | 14篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
Methods for culture ofBombyx mori wing discs 总被引:1,自引:0,他引:1
Hideki Kawasaki 《Methods in Cell Science》1989,12(1):31-33
Summary A culture method forBombyx wing discs is described. Grace's insect medium,Bombyx hemolymph, and moderate doses of ecdysterone (0.02 to 0.1 µg/ml) were necessary for complete imaginal differentiation ofBombyx wing discs. This procedure is useful for understanding ecdysteroid action on insect imaginal differentiation and metamorphosis. 相似文献
82.
S. Oh-ishi Takako Kizaki Tomomi Ookawara Koji Toshinai Shukoh Haga Fujio Karasawa Tetsuo Satoh Naokazu Nagata L. L. Ji Hideki Ohno 《Pflügers Archiv : European journal of physiology》1998,435(6):767-774
The aim of the current study was to elucidate the synergism of dietary calcium restriction and exhaustive exercise in the
antioxidant enzyme system of rat soleus muscle, and to investigate the involvement of neutrophils in exercise-induced muscle
damage. Forty-eight male Wistar rats were assigned to the following groups: control (C) or calcium-restricted [1 month (1 M)
or 3 months (3 M)]. Each group was subdivided into acutely exercised or non-exercised groups. Soleus muscle from each rat
was analysed to determine the levels of antioxidant enzymes [Mn-superoxide dismutase (SOD), Cu,Zn-SOD, glutathione peroxidase
(GPX), and catalase (CAT)]. Dietary calcium restriction resulted in calcium deficiency and upregulated the antioxidant enzymes
examined except GPX. Conversely, exhaustive exercise significantly decreased GPX and CAT, but not SODs activities in the calcium-restricted
(1 M and/or 3 M) rats. Contents of immunoreactive Mn-SOD and Cu,Zn-SOD were only increased in the 3 M rats. During calcium
restriction, the mRNA expression of both forms of SOD showed initial upregulation, followed by downregulation. Exhaustive
exercise significantly increased the mRNA expressions only in the 3 M rats. Moreover, exhaustive exercise markedly increased
myeloperoxidase activity in soleus muscles from the 1 M and 3 M rats compared with the C rats, and significantly enhanced
the ability of neutrophils to generate superoxide in the 3 M rats. The results demonstrate that dietary calcium restriction
upregulates certain antioxidant enzyme activities in rat soleus muscle, indicating an enhanced resistance to potential increases
in intracellular reactive oxygen species. The results also suggest that exhaustive exercise may cause oxidative damage in
soleus muscle of calcium-deficient rats through the activation of neutrophils.
Received: 4 August 1997 / Received after revision: 29 September 1997 / Accepted: 26 November 1997 相似文献
83.
Hideki Tamura Yasuyuki Ishikawa Noriko Hino Maoko Maeda Shigeru Yoshida Shinsuke Kaku Sadao Shiosaka 《The Journal of physiology》2006,570(3):541-551
Long-term potentiation (LTP) is thought to be particularly important in the acquisition of hippocampus-associated memory, in part because it develops quickly and persists for indefinite periods. Extracellular proteolysis has been hypothesized to contribute to LTP by modifying adhesive relations of synapses and thus the morphology of excitatory synapses. Here we report that neuropsin (NP), an extracellular serine protease, is critically involved in the formation of both the potentiation effect and hippocampus-dependent forms of memory. NP-knockout mice were significantly impaired in the Morris water maze and Y-mazes and failed to exhibit early phase LTP induced by a single tetanus. Potentiation was also impaired or completely blocked by in vivo application of a specific inhibitor or a neutralizing monoclonal antibody for NP. Intriguingly, recombinant (r-) NP alone, without tetanic stimulation, elicited either long-lasting potentiation or depression, depending on the applied dose. The r-NP-elicited potentiation was occluded by prior induction of LTP, while theta-burst-elicited LTP was occluded by application of r-NP alone, suggesting that the two forms of plasticity have a common signalling pathway. r-NP-elicited potentiation and depression increased phosphorylation at different sites on the GluR1 subunit of the AMPA receptor that had previously been associated with LTP or long-term depression. Thus, we conclude that NP is necessary for establishment of LTP and has a significant role in memory acquisition. 相似文献
84.
Naoki Yoshimi Chiken Shibuya Yukio Morishita Takuji Tanaka Hideki Mori 《Pathology international》1993,43(12):730-735
The relationship between the numerical aberrations of chromosome 7 in interphase cells and the clinicopathological behavior of breast tumors was investigated in 51 touch imprinted preparations of breast tumors. Using fluorescence in situ hybridization with a chromosome 7-specific DNA probe, the fluoresceinisothiocyanate (FITC) spots mean and the representative copy number of each breast tumor were examined. The FITC spots mean (2.34) of 40 breast cancers increased compared with that of 11 benign lesions (1.98) (P < 0.02). The FITC spots mean tended to increase with the advancing stage and tumor size of the breast cancer. The FITC spots mean in the case with metastasis was also of a higher value than that without metastasis (P < 0.01). Furthermore, the existence of trisomy or over-trisomy of the copy number was related to the advancing stage and tumor size (P < 0.05 and P < 0.01, respectively). These findings suggest that the FITC spots mean and polysomy of the number of chromosome 7 may be highly predictive for breast tumor aggressiveness. 相似文献
85.
Kawada T Yamamoto K Kamiya A Ariumi H Michikami D Shishido T Sunagawa K Sugimachi M 《The Japanese journal of physiology》2005,55(3):157-163
The dynamic characteristics of the baroreflex neural arc from pressure input to efferent sympathetic nerve activity (SNA) reveal derivative characteristics in the frequency range of 0.01 to 0.8 Hz (i.e., the baroreflex gain augments with increasing frequency) and high-cut characteristics in the frequency range above 0.8 Hz (i.e., the baroreflex gain decreases with increasing frequency) in rabbits. The derivative characteristics accelerate the arterial pressure regulation via the baroreflex. The high-cut characteristics preserve the baroreflex gain against pulsatile pressure by attenuating the high-frequency components less necessary for arterial pressure regulation. However, to what extent the carotid sinus baroreceptor transduction from pressure input to afferent baroreceptor nerve activity (BNA) contributes to these characteristics remains unanswered. To test the hypothesis that the carotid sinus pressure-BNA transduction partly explains the derivative characteristics but not the highcut characteristics, we examined the dynamic BNA response to pressure input in the frequency range from 0.01 to 3 Hz by using a white noise analysis in 7 anesthetized rabbits. The transfer function from pressure input to BNA showed slight derivative characteristics in the frequency range from 0.01 to 0.3 Hz with approximately a 1.7-fold increase in dynamic gain, but it showed no high-cut characteristics. In conclusion, the carotid sinus baroreceptor transduction partly explained the derivative characteristics but not the high-cut characteristics of the baroreflex neural arc. The present results suggest the importance of the central processing from BNA to efferent SNA to account for the overall dynamic characteristics of the baroreflex neural arc. 相似文献
86.
Redistribution of fibroblasts and macrophages as micrometastases develop into established liver metastases 总被引:1,自引:0,他引:1
Higashi N Ishii H Fujiwara T Morimoto-Tomita M Irimura T 《Clinical & experimental metastasis》2002,19(7):631-638
Fibroblastic tissue is an important component of malignant tumors, involved in the establishment of metastatic foci from micrometastases,
and thought to prevent invasion of metastatic tumor cells into surrounding tissue. However, experimental models of fibrosis
during the growth of micrometastasis into established metastases were not previously available. In the present paper, we performed
immunohistochemical studies on experimental hepatic metastasis with colon 38 mouse colon carcinoma cells injected into syngeneic
C57BL/6 mice. Early and late stages of metastatic nodules were examined for the distribution of endothelial cells, fibroblasts,
and macrophages by the use of markers of these cells. One week after intrasplenic injection of colon 38 cells, micrometastases
mainly appeared in the region of sinusoids accompanied with invasion of F4/80-positive Kupffer cells. Transitional metastases
can be defined based on the histological appearance and intensive infiltration of both macrophages and fibroblasts. These
transitional metastases were connected by protrusions of fibroblast-rich tissues co-localized with collagen-rich matrix and
CD31-positive cells. This protrusion preceded fibrosis formation characteristics to established metastases associated with
angiogenesis and segregation of tumor cells from host cells. Three stages can thus be classified during the development of
hepatic metastasis in this syngeneic experimental system: micrometastasis, transitional metastasis, and established metastasis.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
87.
Mice lacking smooth muscle calponin display increased bone formation that is associated with enhancement of bone morphogenetic protein responses 总被引:5,自引:0,他引:5
88.
H Hiratsuka M Imamura K Kasai H Kamiya Y Ishii G Kohama K Kikuchi 《American journal of clinical pathology》1984,81(4):464-470
A series of T-cell-specific monoclonal antibodies (Leu-1, Leu-2a, and Leu-3a) and B-cell-specific monoclonal antibody (HLB-1) were used to detect the localization and intensity of infiltration of lymphocyte subpopulations and T-cell subsets in frozen sections of 17 patients with the oral cancer. The vast majority of the lymphocyte infiltrates in the oral cancer tissues were reactive with Leu-1. In contrast, B cells were detectable with HLB-1 in only 2 of 17 cases. Leu-2a-positive cells were dominant in four cases, whereas Leu-3a positive cells were dominant in only three cases. In seven cases, both cells infiltrated to the same degree. Leu-2a positive cells tended to be dominant in the cases with earlier clinical stages. 相似文献
89.
Hideki Endo Takahiro Yonezawa Felix Rakotondraparany Motoki Sasaki Masami Hasegawa 《Annals of anatomy》2006,188(4):383-390
The hindlimb muscles in four species of Tenrecidae (Oryzoryctinae: Talazac long-tailed tenrec and web-footed tenrec, Tenrecinae: lesser hedgehog tenrec, and streaked tenrec), were examined macroscopically. The weight ratios of the muscles to the body in the oryzoryctinid species are larger than those in Tenrecinae, since the Oryzoryctinae species have an obviously smaller body from the evolutionary point of view. It can be primarily pointed out that the adaptation of the body size is different between the two subfamilies, and secondarily, that functional adaptation to locomotion is complete within each subfamily. The weight data and the morphological findings demonstrate that the web-footed tenrec possesses an extraordinary large M. semimembranosus in comparison to the Talazac long-tailed tenrec in their weight ratios. This muscle may act as a strong flexor motor in the knee joint during the aquatic locomotion of the web-footed tenrec. Since the other muscles of the web-footed tenrec are similar to those of the Talazac long-tailed tenrec regards weight ratio data, we think that the web-footed tenrec may have derived from a terrestrial ancestor such as the long-tailed tenrecs. In Tenrecinae the streaked tenrec is equipped with larger Mm. adductores, M. semimembranosus and M. triceps surae than the lesser hedgehog tenrec. This species is adapted to fossorial life derived from non-specialized ancestors within the evolutionary lines of the spiny tenrecs. 相似文献
90.