全文获取类型
收费全文 | 4608篇 |
免费 | 224篇 |
国内免费 | 138篇 |
专业分类
耳鼻咽喉 | 16篇 |
儿科学 | 193篇 |
妇产科学 | 74篇 |
基础医学 | 593篇 |
口腔科学 | 126篇 |
临床医学 | 319篇 |
内科学 | 1107篇 |
皮肤病学 | 41篇 |
神经病学 | 264篇 |
特种医学 | 236篇 |
外科学 | 267篇 |
综合类 | 450篇 |
预防医学 | 522篇 |
眼科学 | 14篇 |
药学 | 542篇 |
1篇 | |
中国医学 | 91篇 |
肿瘤学 | 114篇 |
出版年
2024年 | 12篇 |
2023年 | 65篇 |
2022年 | 171篇 |
2021年 | 297篇 |
2020年 | 179篇 |
2019年 | 139篇 |
2018年 | 143篇 |
2017年 | 140篇 |
2016年 | 142篇 |
2015年 | 131篇 |
2014年 | 296篇 |
2013年 | 398篇 |
2012年 | 193篇 |
2011年 | 262篇 |
2010年 | 176篇 |
2009年 | 236篇 |
2008年 | 212篇 |
2007年 | 227篇 |
2006年 | 161篇 |
2005年 | 182篇 |
2004年 | 125篇 |
2003年 | 109篇 |
2002年 | 95篇 |
2001年 | 91篇 |
2000年 | 63篇 |
1999年 | 57篇 |
1998年 | 71篇 |
1997年 | 58篇 |
1996年 | 34篇 |
1995年 | 53篇 |
1994年 | 49篇 |
1993年 | 45篇 |
1992年 | 55篇 |
1991年 | 33篇 |
1990年 | 37篇 |
1989年 | 22篇 |
1988年 | 19篇 |
1987年 | 13篇 |
1986年 | 19篇 |
1985年 | 29篇 |
1984年 | 23篇 |
1983年 | 18篇 |
1982年 | 14篇 |
1981年 | 15篇 |
1980年 | 11篇 |
1979年 | 9篇 |
1978年 | 10篇 |
1977年 | 7篇 |
1976年 | 7篇 |
1972年 | 4篇 |
排序方式: 共有4970条查询结果,搜索用时 15 毫秒
1.
Prabhakaran Dhanasekaran Swaminathan Rajavarman Sivasuriyanarayanan Vinod Selvaganesh Santoshkumar Dattatray Bhat 《Materials》2021,14(9)
Nanocrystalline platinum with different morphologies is synthesized via electrochemical deposition technique. The nucleation mechanism and its structural effect over the electrodeposited Pt on carbon electrodes have been systematically studied. Powder X-ray diffraction, X-ray photoelectron spectroscopy, and field-emission scanning electron microscopy are employed to study nucleation, oxidation states, and Pt structure growth on a carbon electrode. This study reports significant development of Pt metal nanoparticles with different morphologies such as a sphere, flower, core-flower, and rod-like structure directly fabricated on carbon electrode while tuning the deposition parameters such as current density, time, temperature, pH during the deposition process. The proposed electrochemical route represents a superior fabrication procedure for large-scale electrode fabrication compared to a conventional method for preparing membrane electrode assemblies for fuel cell stacks. 相似文献
2.
Sadanandavalli Retnaswami Chandra Pawan Raj Thomas Gregor Issac 《Indian journal of dermatology》2015,60(3):290-292
Neurodegeneration with brain iron accumulation (NBIA) is the term applied to a heterogeneous group of disorders resulting in iron deposition in the basal ganglia. Well-known phenotypic features are progressive regression with extra pyramidal involvement and a variable course. A 10-year-old child born to consanguineous parents presented with progressive generalized opisthotonic dystonia, retrocollis, oromandibular dyskinesias, apraxia for swallowing, optic atrophy and severe self-mutilation of lips. MR imaging showed brain iron accumulation. Other causes of self-mutilation were excluded. Early infantile onset, ophisthotonic dystonia with oromandibular dyskinesias and characteristic MR images are suggestive of NBIA. There is only one case reported in the literature of self-mutilation in this condition. 相似文献
3.
4.
Ramya Deepthi Vinnakota Allan S. Brett 《The American journal of the medical sciences》2019,357(2):160-163
Iron deficiency anemia is often listed among potential adverse effects of gastric acid-suppressive medications, given that gastric acidity promotes intestinal absorption of nonheme iron. Additionally, the antacid calcium carbonate can inhibit iron absorption. However, there is little direct clinical evidence that proton-pump inhibitors, histamine-2 receptor antagonists, or calcium carbonate cause iron deficiency anemia. Most case reports have had substantial limitations (e.g., minimal follow-up and presence of other causes of iron deficiency), and retrospective cohort studies have lacked sufficient patient-specific detail to make strong causal inferences. We present 2 cases—both with detailed, prospective 10-year follow-up—in which combinations of proton-pump inhibitors, histamine-2 receptor antagonists and calcium carbonate were clearly associated with development of iron deficiency anemia. Overt iron-deficiency anemia is probably uncommon in patients who use acid-modifying medications and who have no other conditions that predispose to iron deficiency. Nevertheless, clinicians should be aware of this potential complication, given widespread use of these agents. 相似文献
5.
6.
7.
Moussa Ndong Machiko Kazami Tsukasa Suzuki Mariko Uehara Shin-ichi Katsumata Hirohumi Inoue Ken-Ichi Kobayashi Tadahiro Tadokoro Kazuharu Suzuki Yuji Yamamoto 《Nutrition Research》2009,29(9):640-647
Iron deficiency (ID) is one of the most commonly known forms of nutritional deficiencies. Low body iron is thought to induce neurologic defects but may also play a protective role against cancer development by cell growth arrest. Thus, ID may affect cellular pathways controlling cell growth and proliferation, the mechanism of which is still not fully understood. The serine/threonine protein kinase Akt and its downstream target, the mammalian Target of Rapamycin (mTOR), is known to play a crucial role in the regulation of cell growth and survival. Therefore, we hypothesized that Akt/mTOR pathway could be influenced by ID. Three-week-old male Wistar-strain rats were divided into 3 groups and the 2 groups had free access to a control diet (C group) or an iron-deficient diet (D group). The third group (PF group) were pair-fed the control diet to the mean intake of the D group. After 4 weeks, rats were killed and their brains were sampled. In separate experiments, COS-1 cells were cultured with or without the iron chelator deferoxamine. Western blots of brain samples and COS-1 lysates were used to analyze the expression and phosphorylation state of Akt, TSC2, mTOR, and S6 kinase proteins implicated in the Akt/mTOR pathway. Using 2 different ID models, we show for the first time that iron deficiency depresses Akt activity in rats and in COS-1 cells, leading to a decrease in mTOR activity. 相似文献
8.
The electrodeposition of Ag on Pt(100)-(1 × 1) in perchlorate electrolyte was studied by means of time-resolved in situ scanning tunnelling microscopy (STM) and cyclic voltammetry. One monolayer of Ag is deposited underpotentially (upd) ca. 500 mV positive of the Ag+/Ag equilibrium potential. Several millivolts positive of the equilibrium potential, a second well defined upd layer forms. Its growth was observed to proceed via island formation and coalescence. This process occurs in two separate stages that manifest themselves in voltammetric peaks as well as in the STM images. 相似文献
9.
铁缺乏时淋巴细胞增殖反应改变的实验研究 总被引:1,自引:0,他引:1
本研究采用体外细胞培养,3H-Tdr掺入,原子吸收光谱分析等技术方法,观察了低浓度Fe-cit时淋巴细胞内铁浓度变化及经ConA、PHA诱导的细胞增殖反应能力改变,结果显示:铁缺乏时(第2、3、4组)SI降低,与正常组(第1组)比较相差非常显著(P<0.01),SI与细胞内铁浓度的变化呈显著正相关(P<0.05,r1=0.9466,r2=0.9339),说明铁缺乏时淋巴细胞增殖反应能力受抑。 相似文献
10.
热力学计算表明,H2,N2的过量有助于提高TiN的产率,但能耗也相应增加。为此考察了温度,流量,TiCl4携带量,混合方式对产物性能的影响。结果表明,流量增加,温度升高,TiCl4携带量增加,混合愈好,则产物粒径愈小。在此基础上采用微波等离子体化学气相沉积法,合成了粒径为123-284nm的TiN超细颗粒 相似文献