全文获取类型
收费全文 | 10956篇 |
免费 | 494篇 |
国内免费 | 77篇 |
专业分类
耳鼻咽喉 | 117篇 |
儿科学 | 194篇 |
妇产科学 | 71篇 |
基础医学 | 1366篇 |
口腔科学 | 252篇 |
临床医学 | 693篇 |
内科学 | 3185篇 |
皮肤病学 | 153篇 |
神经病学 | 645篇 |
特种医学 | 405篇 |
外科学 | 1802篇 |
综合类 | 42篇 |
一般理论 | 1篇 |
预防医学 | 183篇 |
眼科学 | 132篇 |
药学 | 659篇 |
中国医学 | 14篇 |
肿瘤学 | 1613篇 |
出版年
2023年 | 93篇 |
2022年 | 216篇 |
2021年 | 353篇 |
2020年 | 181篇 |
2019年 | 234篇 |
2018年 | 277篇 |
2017年 | 225篇 |
2016年 | 279篇 |
2015年 | 269篇 |
2014年 | 335篇 |
2013年 | 415篇 |
2012年 | 724篇 |
2011年 | 820篇 |
2010年 | 473篇 |
2009年 | 370篇 |
2008年 | 671篇 |
2007年 | 689篇 |
2006年 | 681篇 |
2005年 | 642篇 |
2004年 | 601篇 |
2003年 | 594篇 |
2002年 | 585篇 |
2001年 | 148篇 |
2000年 | 159篇 |
1999年 | 149篇 |
1998年 | 121篇 |
1997年 | 95篇 |
1996年 | 66篇 |
1995年 | 84篇 |
1994年 | 68篇 |
1993年 | 60篇 |
1992年 | 89篇 |
1991年 | 95篇 |
1990年 | 83篇 |
1989年 | 75篇 |
1988年 | 63篇 |
1987年 | 60篇 |
1986年 | 56篇 |
1985年 | 50篇 |
1984年 | 37篇 |
1983年 | 33篇 |
1982年 | 23篇 |
1981年 | 17篇 |
1980年 | 10篇 |
1979年 | 23篇 |
1978年 | 12篇 |
1977年 | 22篇 |
1972年 | 10篇 |
1969年 | 14篇 |
1967年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
It has been reported that neurons in the orbitofrontal cortex (OFC) respond to emotionally significant events such as reward-predicting cues and/or the reward itself. The responses to reward-predicting cues are considered to carry the information of the predicted reward. However, few studies have focused on the relationship of the neuronal activity during a cue period with that during a reward period. We can infer that the cue responses of OFC neurons are correlated to the reward responses if they carry the information of the predicted reward. In this study, we focused on neurons that showed responses during both the cue and reward periods, and compared the response characteristics between these periods. We found 94 of 369 OFC neurons showed significant responses during both the cue and reward periods, and 43 of which preserved their selectivity between these periods. Furthermore, population analysis showed that stronger cue responses corresponded to stronger reward responses, and stronger reward responses corresponded to stronger cue responses. These results suggest that individual neurons in the OFC associate visual information with reward information, and contribute to the prediction of future rewards by forming reward representations. 相似文献
92.
Tsuneyuki Sato Masaki Takada Takayuki Otsu 《Macromolecular chemistry and physics.》1971,148(1):239-249
A study of vinyl polymerizations initiated with the system of dimethylaniline (DMA) and cupric [Cu(II)] nitrate has been made. This initiator system was found to induce the polymerization of vinyl monomers having an electron-attracting substituent such as methyl methacrylate (MMA) and acrylonitrile, but it does not initiate the styrene and vinyl acetate polymerizations. The rate of polymerization (Rp) of MMA with this system was expressed by the following Eqs., depending upon the Cu(II) concentration used: The apparent activation energy for this polymerization was found to be 16.5 and 14.4 kcal/mole for the above two Cu(II) concn. ranges, respectively. The polymer of MMA obtained by this system was found to contain an endgroup similar to dimethylaniline, probably a methylanilinomethyl group, from the determination of its UV spectrum. 相似文献
93.
We have previously demonstrated that p100H mutant mice, which lack a functional Sox6 gene, exhibit skeletal and cardiac muscle degeneration and develop cardiac conduction abnormalities soon after birth. To understand the role of Sox6 in skeletal muscle development, we identified muscle-specific genes differentially expressed between wild-type and p100H mutant skeletal muscles and investigated their temporal expression in the mutant muscle. We found that, in the mutant skeletal muscle, slow fiber and cardiac isoform genes are expressed at significantly higher levels, whereas fast fiber isoform genes are expressed at significantly lower levels than wild-type. Onset of this aberrant fiber type-specific gene expression in the mutant coincides with the beginning of the secondary myotube formation, at embryonic day 15-16 in mice. Together with our earlier report, demonstrating early postnatal muscle defects in the Sox6 null-p100H mutant, the present results suggest that Sox6 likely plays an important role in muscle development. 相似文献
94.
Distribution of the binding sites of Joro spider toxin (JSTX), a specific inhibitor of the glutamate receptors in the crustacean neuromuscular synapse, was studied by using autoradiography. JSTX was synthesized and made radioactive by conjugation with iodine-125. 125I-JSTX irreversibly blocked the excitatory postsynaptic potentials of the lobster neuromuscular synapse in a similar manner as the natural spider toxin. Light microscopic autoradiography of 125I-JSTX treated muscle showed sporadic aggregates of reduced silver grains on the surface of muscles. Electron microscopy of adjoining ultrathin sections revealed that these spots corresponded to the fraction of sarcolemma apposed to axonal terminals with or without synaptic junctional profiles. This finding gives morphological support to the formulation that JSTX binds to the glutamate receptor-ion channel molecules. 相似文献
95.
96.
Hagiwara K Nakagawasai O Murata A Yamadera F Miyoshi I Tan-No K Tadano T Yanagisawa T Iijima T Murakami M 《Neuroscience research》2003,46(4):493-497
We investigated the relationship between the antinociceptive effect of the opiate agonist loperamide at the spinal level and its inhibitory effect on calcium influx. Intrathecal administration of loperamide showed a significant antinociceptive effect in the formalin test, which was not prevented by naloxone. On the other hand, no significant effects were observed by nicardipine, an L-type specific blocker, or by BAY K8644, an L-type specific agonist, suggesting no significant role of L-type calcium channels in nociceptive signal transduction. Loperamide suppressed the calcium influx in dorsal root ganglion neurons. As the antinociceptive effect of loperamide was not affected by naloxone or other calcium channel blocking toxins, and loperamide showed a direct inhibitory effect on calcium-influx, the analgesic effect of intrathecally injected loperamide might be due to its blockade of the voltage-dependent calcium channels at the terminals of the primary afferent fibers. 相似文献
97.
Akiko Aoki Shigeru Ono Atsuhisa Ueda Eri Hagiwara Tsuji Takashi Haruko Ideguchi Midori Misumi Tetsuo Sasaki Yoshio Ikezawa Yoshiaki Inayama Yuko Inoue Yoshiaki Ishigatsubo 《Nihon Rinshō Men'eki Gakkai kaishi》2002,25(2):205-211
We described two female patients with primary Sj?gren's syndrome associated with localized cutaneous nodular amyloidosis (LCNA), in which amyloid protein was derived from immunoglobulin light chain. Case 1; a 70-year-old female had complained with polyarthralgia, low-grade fever and parotid gland swelling. She was diagnosed as primary Sj?gren's syndrome. Three years later she noticed brown color small tumor on the thigh and yellow to brown nodules on the bilateral calves of legs. Skin biopsy from the left thigh revealed amyloid L protein deposition, which was positive for anti-lambda light chain staining, in almost entire dermis. Infiltration of lymphocytes and plasma cells around the amyloid deposit were prominent. Case 2; a 51-year-old female had noticed increasing eruption on the hip. Skin biopsy revealed amyloid L protein deposition in the dermis, which was negative for anti-lambda nor kappa light chain staining. When she was refereed to our hospital, she complained of xerostomia and xerophthalmia. She was diagnosed as primary Sj?gren's syndrome. In both cases, histological examination of a minor salivary gland biopsy revealed infiltration of lymphocytes and plasma cells but not amyloid deposit. Serum M protein and urine Bence-Jones protein were not detected. These cases represent localized amyloidosis without systemic involvement. It is widely recognized that Sj?gren's syndrome is frequently accompanied by B cell lymphoproliferative disorders. In LCNA, infiltration of plasma cells around the amyloid deposits was frequently prominent. The relation between these two disorders is discussed. 相似文献
98.
Yang-Un Mun Tsuneyuki Sato Takayuki Otsu 《Macromolecular chemistry and physics.》1984,185(8):1493-1505
The effect of some metallocenes such as ferrocene (Fe(C5H5)2), nickelocene (Ni(C5H5)2), and cobaltocene (Co(C5H5)2), on the vinyl polymerization initiated with bis(ethyl acetoacetato)-copper(II) (Cu(eacac)2) was investigated. Co(C5H5)2 was found to exert a markedly accelerating effect on the polymerization of methyl methacrylate (MMA) with Cu(eacac)2. The polymerization of MMA with the system Co(C5H5)2/Cu(eacac)2 at 50°C was found to be fairly affected by the solvent used. The results of copolymerization of MMA with styrene (St) and the effect of hydroquinone (HQ) on the polymerization of MMA with Co(C5H5)2/Cu(eacac)2 showed that the polymerization proceeds via a radical mechanism. The polymerization of MMA with Co(C5H5)2/Cu(eacac)2 was studied kinetically in acetone. The overall activation energy of the polymerization was calculated to be 86,3 kJ/mol (20,6 kcal/mol). This value was somewhat higher than that (17,6 kcal/mol) obtained for the polymerization of MMA with Cu(eacac)2 alone. The polymerization rate (Rp) is represented by the following equation: Rp = k[Co(C5H5)2]0,5 [Cu(eacac)2]0,2 [MMA]1,3. The high order in monomer concentration suggests a participation of the monomer in the initiation process of this polymerization. This is supported by the examination of the ESR spectrum of the system Co(C5H5)2/Cu(eacac)2/MMA/acetone, where reduction of Cu(II) to Cu(I) occurs. To elucidate the initiation mechanism, the spin trapping technique was applied to the system Co(C5H5)2/Cu(eacac)2/methyl acrylate. From these results, an initiation mechanism for the binary initiator system Co(C5H5)2/Cu(eacac)2 is proposed and discussed. 相似文献
99.
Masahiro Kamouchi Takanari KitazonoTetsuro Ago Masanori WakisakaJunya Kuroda Kuniyuki NakamuraNoriko Hagiwara Hiroaki OoboshiSetsuro Ibayashi Mitsuo Iida 《Neuroscience letters》2007
Objective: The aims of the present study were to elucidate the interaction of reactive oxygen species (ROS) and Ca2+ response in central nervous system (CNS) pericytes. Methods: The intracellular Ca2+ concentration was measured using fluorescent Ca2+ indicator, fura-2, in cultured CNS pericytes. Results: Hydrogen peroxide evoked a dose-dependent increase in cytosolic Ca2+, which was completely inhibited by catalase. Removal of external Ca2+ or addition of nicardipine (1 μM) during application of hydrogen peroxide did not affect Ca2+ response. Incubation of the cells in Ca2+ free solution did not abolish but slightly reduced Ca2+ response by hydrogen peroxide. Ca2+ response to hydrogen peroxide was not altered by the depletion of intracellular Ca2+ by thapsigargin (1 μM). Pretreatment of the cells with tyrosine kinase inhibitor genistein (100 μM) or tyrphostin A47 (30 μM) significantly reduced Ca2+ increase by hydrogen peroxide. Conclusions: These results indicate that hydrogen peroxide evokes Ca2+ increase predominantly by release from intracellular Ca2+ store, which may be regulated by tyrosine kinases. 相似文献
100.
Tadashi Narita Tokio Hagiwara Hiroshi Hamana Tomihiro Kurashima 《Macromolecular chemistry and physics.》1987,188(1):1-6
The lithium alkylamide catalyzed addition reaction of α-methylbenzylamine ( 1 ) with styrene was found to produce selectively N-phenethyl-α-methylbenzylamine ( 3 ). Under the same reaction conditions, addition of (S)-α-methylbenzylamine ( 1 ′) to 1,4-divinylbenzene ( 5 ) takes place selectively leading to the optically active novel styrene derivative, (S)-N-α-methylbenzyl-4-vinylphenethylamine ( 6 ), in a one-step reaction. The specific rotation was found to be [α]4D = ?70,1° (c = 1,61 g/dl, in methanol). The following Q, e-values and the monomer reactivity rations of 6 (M1) and styrene ( M 2) were obtained: Q1 = 1,59, e1 = ?1,28; r1 = 0,86, r2 = 0,92. 相似文献